HomeMy WebLinkAboutSFRA2007-2751THE FOLLOWING IS TO BE COMPLETED BY THE BUILDING INSPECTION DEPARTMENT
Construction T e:' .
Permit Valuation; $
Setbacks
A roval to Issue
Oceu ancy Group:'
Front;
Electrical t . t,
Division:
Building Width:
Left;
Plumbin
Zoning:
Building D ` th;
Ri t:
Mechanical
Rear:
Plan Review A roval:
Date:
Water Availability Rate:
Site Plan Approval:
Date: V
Sewer Availability Rate;
Fire Department:
Date:
Building Permit Fee:
Public Works Department:
,Date:
Plan Review Fee:
Health Department:
Date:
Lot Drainage Fee:
Approved for Permit:
Date:
Total Fees:
Lot. Drainage Submitted:
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Approved:
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Total; Amount Due:
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September 18, 2007
Ross Bannister
424 Ball Street
Grapevine, Texas 76051
Re: Rainwater Harvesting System, 424 Ball Street
Dear Ross,
I have received and reviewed your proposed rainwater harvesting system for potable
and nonpotable use. A simplified analysis of the plans and specifications is as follows:
The plans and specifications submitted show a cistern (holding tank) that collects runoff
from the roof of the single family residence. This cistern also receives supply from the
Public Water Supply. The discharge from the PWS is protected from cross connection
by an airgap. Additionally the PWS is protected downstream of the water meter with a
double check valve. Another double check valve is shown to be installed between the
irrigation system and the domestic water supply.
I have spoken with the Public Works Department, and their only concern has been the
protection of the Public Water Supply; they have no requirements whatsoever for private
water supplies.
I have also consulted the Tarrant County Environmental Health Department, Texas
Commission on Environmental Quality, as well as the Texas Water Development Board
and the Rainwater Harvesting Evaluation Board Committee's report, all of which have
provided guidance relative to these systems.
Although the plumbing code adopted by the City does not recognize/permit this type of
system, I am prepared to release this proposed system for construction with the
following conditions:
1) At no time may the airgap connection between the cistern and Public Water
Supply be compromised
2) Both double check valve assemblies shall tested by a testing agency licensed
by the State of Texas. Test results shall be documented on forms available in
the Building Department, and these completed forms shall be submitted back
to the Building Department when the testing is complete.
DEVELOPMENT SERVICES DEPARTMENT
The City of Grapevine • P O Box 95104 • Grapevine, Texas 76099 • (817) 410-3154
Fax (817) 410-3018 • www.ci.grapevine.tx.us
3) At the time of final inspection, a report shall be submitted to the Building
Department documenting the quality of the water from a plumbing fixture in
the house. The report shall be submitted by a laboratory that is accredited by
the TCEQ. A list of accredited laboratories may be found on the TCEQ
website at www.tceg.state.tx.us/complancecompliance support/a/env
lab accredition.html. The report shall provide evidence of the following
water quality standards:
Total Coliform -0
Fecal Coliform- 0
Protozoan Cysts - 0
Turbidity< 1 NTU
4) An affidavit shall be filed with the property deed notifying future property
owners by stating the nature of the system and the requirements for
maintenance. The language of this affidavit shall be developed jointly
between the City Attorney, the Building Department, and yourself.
Please be advised that the City of Grapevine is in no way providing approval of this
system, or it's operation and performance. I am simply releasing it for construction
based upon the above conditions being met. Inspections will be performed to ensure
that the PWS is not compromised, and that the conventional components of the
plumbing system are code -compliant, but no inspections will be performed on the
harvesting system itself. Please do not hesitate to contact me .f You havo ai y
questions.
y
Williams
(Building Official
cc: H. T. (Tommy) Hardy, Assistant City Manager
Matthew Boyle, City Attorney
Matt Singleton, Public Works Director
Stan Laster, Public Works Deputy Director
Jerry Cool, Plans Examiner
Don Ellison, Plans Examiner
Nathan Loftice, Environmental Manager
David Jefferson, Tarrant County Environmental Health Department
0:\SW\2007\rainwaterharvesting.doc
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Texas Commission on Environmental Quality
Figure: 30 TAC §290.47(i)
Page I of 4
Appendix 1: Assessment of Hazards and Selection of Assemblies
The following table lists many common hazards. It is not an all-inclusive list of the hazards
which may be found connected to
public water systems.
Premises Isolation - Description of
Assessment of
Required
Premises
Hazard
Assembly
Aircraft and missile plants
Health
RPBA or AG
Animal feedlots
Health
RPBA or AG
Automotive plants
Health
RPBA or AG
Breweries
Health
RPBA or AG
Canneries, packing houses and rendering
Health
RPBA or AG
plants
Commercial car wash facilities
Health
RPBA or AG
Commercial laundries
Health
RPBA or AG
Cold storage facilities
Health
RPBA or AG
Connection to sewer pipe
Health
RPBA or AG
Dairies
Health
RPBA or AG
Docks and dockside facilities
Health
RPBA or AG
Dye works
Health
RPBA or AG
Food and beverage processing plants
Health
RPBA or AG
Hospitals, morgues, mortuaries, medical
clinics,
dental clinics, veterinary clinics, autopsy
facilities,
sanitariums, and medical labs
Health
RPBA or AG
Metal manufacturing, cleaning, processing,
and fabrication plants
Health
RPBA or AG
Microchip fabrication facilities
Health
RPBA or AG
Paper and paper products plants
Health
RPBA or AG
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Texas Commission on Environmental Quality Page 2 of 4
Petroleum processing or storage facilities
Health
RPBA or AG
Photo and film processing labs
Health
RPBA or AG
Plants using radioactive material
Health
RPBA or AG
Plating or chemical plants
Health
RPBA or AG
Pleasure -boat marinas
Health
RPBA or AG
Private/Individual/Unmonitored Wells
Health
RPBA or AG
Reclaimed water systems
Health
RPBA or AG
Restricted, classified or other closed facilities
Health
RPBA or AG
Rubber plants
Health
RPBA or AG
Sewage lift stations
Health
RPBA or AG
Sewage treatment plants
Health
RPBA or AG
Slaughter houses
Health
RPBA or AG
Steam plants
Health
RPBA or AG
Tall buildings or elevation differences where
the
highest outlet is 80 feet or more above the
meter
Nonhealth
DCVA
Internal Protection - Description of Cross
Assessment of
Required
Connection
Hazard
Assembly
Aspirators
Nonhealtht
AVB
Aspirator (medical)
Health
AVB or PVB
Autoclaves
Health
RPBA
Autopsy and mortuary equipment
Health
AVB or PVB
Bedpan washers
Health
AVB or PVB
Connection to industrial fluid systems
Health
RPBA
Connection to plating tanks
Health
RPBA
Connection to salt -water cooling systems
Health
RPBA
Connection to sewer pipe
Health
AG
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Texas Commission on Environmental Quality Page 3 of 4
Cooling towers with chemical additives
Health
AG
Cuspidors
Health
AVB or PVB
Degreasing equipment
Nonhealtht
DCVA
Domestic space -heating boiler
Nonhealtht
RPBA
Dye vats or machines
Health
RPBA
Fire -fighting system
Nonhealtht
(toxic liquid foam concentrates)
Health
RPBA
Flexible shower heads
Nonhealtht
AVB or PVB
Heating equipment
Nonhealtht
PVB or AG
Commercial
Nonhealtht
RPBA
Domestic
Nonhealtht
DCVA
Hose bibbs
Nonhealtht
AVB
Irrigation systems
with chemical additives
Health
RPBA
without chemical additives
Nonhealtht
DCVA, AVB, or
PVB
Kitchen equipment - Commercial
Nonhealtht
AVB
Lab bench equipment
Health or
AVB or PVB
Nonhealtht
Ornamental fountains
Health
AVB or PVB
Swimming pools
Private
Nonhealtht
PVB or AG
Public
Nonhealtht
RPBA or AG
Sewage pump
Health
AG
Sewage ejectors
Health
AG
Shampoo basins
Nonhealtht
AVB
Specimen tanks
Health
AVB or PVB
Steam generators
Nonhealtht
RPBA
Steam tables
Nonhealtht
AVB
Sterilizers
Health
RPBA
Tank vats or other vessels containing toxic
http://info.sos,state.tx.us/fids/30-0290-0047-'l2.htmi
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Texas Commission on Environmental Quality
substances
Trap primers
Vending machines
Watering troughs
Page 4 of 4
Health RPBA
Health AG
i mom ; M -t M V a 0.7-I'Vey a iyj 0.1
Health AG or PVB
NOTE: AG = air gap; AVB = atmospheric vacuum breaker; DCVA = double check valve
backflow prevention
assembly; PVB = pressure vacuum breaker; RPBA = reduced -pressure principle backflow
prevention assembly.
*AVBs and PVBs may be used to isolate health hazards under certain conditions, that is,
backsiphonage situations.
Additional area of premises isolation may be required.
tWhere a greater hazard exists (due to toxicity or other potential health impact) additional area
protection
with RPBAs is required.
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Texas Administrative Code
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ENVIRONMENTAL QUALITY
TEXAS COMMISSION ON ENVIRONMENTAL
QUALITY
PUBLIC DRINKING WATER
SYSTEMS
RULE §290.38 Definitions
The following words and terms, when used in this chapter shall have the following
meanings, unless the context clearly indicates otherwise. If a word or term used in this
chapter is not contained in the following list, its definition shall be as shown in Title 40
Code of Federal Regulations (CFR) 141.2. Other technical terms used shall have the
meanings or definitions listed in the latest edition of The Drinking Water Dictionary,
prepared by the American Water Works Association.
(1) Air gap --The unobstructed vertical distance through the free atmosphere between
the lowest opening from any pipe or faucet conveying water to a tank, fixture, receptor,
sink, or other assembly and the flood level rim of the receptacle. The vertical, physical
separation must be at least twice the diameter of the water supply outlet, but never less
than 1.0 inch.
(2) ANSI standards --The standards of the American National Standards Institute, Inc.,
1430 Broadway, New York, New York 10018.
(3) Approved laboratory --A laboratory certified and approved by the commission to
analyze water samples to determine their compliance with maximum allowable
constituent levels.
(4) ASME standards --The standards of the American Society of Mechanical Engineers,
346 East 47th Street, New York, New York 10017.
(5) ASTM standards --The standards of the American Society for Testing and Materials,
1916 Race Street, Philadelphia, Pennsylvania 19102.
(6) Auxiliary power --Either mechanical power or electric generators which can enable
the system to provide water under pressure to the distribution system in the event of a
local power failure. With the approval of the executive director, dual primary electric
service may be considered as auxiliary power in areas which are not subject to large
scale power outages due to natural disasters.
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Page 2 of 7
(7) AWWA standards --The latest edition of the applicable standards as approved and
published by the American Water Works Association, 6666 West Quincy Avenue,
Denver, Colorado 80235.
(8) Certified laboratory --A laboratory certified by the commission to analyze water
samples to determine their compliance with maximum allowable constituent levels.
(9) Community water system --A public water system which has a potential to serve at
least 15 residential service connections on a year-round basis or serves at least 25
residents on a year-round basis.
(10) Connection A single family residential unit or each commercial or industrial
establishment to which drinking water is supplied from the system. As an example, the
number of service connections in an apartment complex would be equal to the number of
individual apartment units. When enough data is not available to accurately determine
the number of connections to be served or being served, the population served divided
by three will be used as the number of connections for calculating system capacity
requirements. Conversely, if only the number of connections is known, the connection
total multiplied by three will be the number used for population served. For the purposes
of this definition, a dwelling or business which is connected to a system that delivers
water by a constructed conveyance other than a pipe shall not be considered a
connection if
(A) the water is used exclusively for purposes other than those defined as human
consumption (see human consumption);
(B) the executive director determines that alternative water to achieve the equivalent
level of public health protection provided by the drinking water standards is provided for
residential or similar human consumption, including, but not limited to, drinking and
cooking; or
(C) the executive director determines that the water provided for residential or similar
human consumption is centrally treated or is treated at the point of entry by a provider, a
pass through entity, or the user to achieve the equivalent level of protection provided by
the drinking water standards.
0 1) Contamination --The presence of any foreign substance (organic, inorganic,
radiological or biological) in water which tends to degrade its quality so as to constitute
a health hazard or impair the usefulness of the water.
(12) Cross-connection—A physical connection between a public water system and
either another supply of unknown or questionable quality, any source which may contain
contaminating or polluting substances, or any source of water treated to a lesser degree
in the treatment process.
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(13) Disinfectant --Any oxidant, *including but not limited to chlorine, chlorine dioxide,
chloramines, and ozone added to the water in any part of the treatment or distribution
process, that is intended to kill or inactivate pathogenic microorganisms.
(14) Disinfection --A process which inactivates pathogenic organisms in the water by
chemical oxidants or equivalent agents.
(15) Distribution system --A system of pipes that conveys potable water from a
treatment plant to the consumers. The term includes pump stations, ground and elevated
storage tanks, potable water mains, and potable water service lines and all associated
valves, fittings, and meters, but excludes potable water customer service lines.
(16) Drinking water --All water distributed by any agency or individual, public or
private, for the purpose of human consumption or which may be used in the preparation
of foods or beverages or for the cleaning of any utensil or article used in the course of
preparation or consumption of food or beverages for human beings. The term "Drinking
Water" shall also include all water supplied for human consumption or used by any
institution catering to the public.
(17) Drinking water standards --The commission rules covering drinking water
standards in Subchapter F of this chapter (relating to Drinking Water Standards
Governing Drinking Water Quality and Reporting Requirements for Public Water
Systems).
(18) Elevated storage capacity --That portion of water which can be stored at least 80
feet above the highest service connection in the pressure plane served by the storage
tank.
(19) Emergency power --Either mechanical power or electric generators which can
enable the system to provide water under pressure to the distribution system in the event
of a local power failure. With the approval of the executive director, dual primary
electric service may be considered as emergency power in areas which are not subject to
large scale power outages due to natural disasters.
(20) Groundwater --Any water that is located beneath the surface of the ground and is
not under the direct influence of surface water.
(2 1) Groundwater under the direct influence of surface water --Any water beneath the
surface of the ground with:
(A) significant occurrence of insects or other macroorganisms, algae, or large -
diameter pathogens such as Giardia lamblia or Ct-yptosporidhnn; or
(B) significant and relatively rapid shifts in water characteristics such as turbidity,
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temperature, conductivity, or pH which closely correlate to climatological or surface
water conditions.
(22) Health hazard --A cross -connection, potential contamination hazard, or other
situation involving any substance that can cause death, illness, spread of disease, or has a
high probability of causing such effects if introduced into the potable drinking water
supply.
(23) Human consumption --Uses by humans in which water can be ingested into or
absorbed by the human body. Examples of these uses include, but are not limited to
drinking, cooking, brushing teeth, bathing, washing hands, washing dishes, and
preparing foods.
(24) Interconnection --A physical connection between two public water supply systems.
(25) Intruder -resistant fence --A fence six feet or greater in height, constructed of wood,
concrete, masonry, or metal with three strands of barbed wire extending outward from
the top of the fence at a 45 degree angle with the smooth side of the fence on the outside
wall. In lieu of the barbed wire, the fence must be eight feet in height. The fence must be
in good repair and close enough to surface grade to prevent intruder passage,
(26) L/d ratio --The dimensionless value that is obtained by dividing the length (depth)
of a granular media filter bed by the weighted effective diameter "d" of the filter media.
The weighted effective diameter of the media is calculated based on the percentage of
the total bed depth contributed by each media layer.
(27) Licensed professional engineer --An engineer who maintains a current license
through the Texas Board of Professional Engineers in accordance with its requirements
for professional practice.
(28) Maximum daily demand --In the absence of verified historical data or in cases
where a public water system has imposed mandatory water use restrictions within the
past 36 months, maximum daily demand means 2.4 times the average daily demand of
the system.
(29) Maximum contaminant level (MCL) --The MCL for a specific contaminant Is
defined in the section relating to that contaminant.
(30) Milligrams per liter (mg/L)--A measure of concentration, equivalent to and
replacing parts per million in the case of dilute solutions.
(3 1) Monthly reports of water works operations --The daily record of data relating to the
operation of the system facilities compiled in a monthly report.
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(32) National Fire Protection Association (NFPA) standards --The standards of the
NFPA I Batteryniarch Park, Quincy, Massachusetts, 02269-9101.
(33) National Sanitation Foundation (NSF) --The NSF or reference to the listings
developed by the foundation, P.O. Box 1468, Ann Arbor, Michigan 48106.
(34) Noncommunity water system --Any public water system which is not a community
system,
(35) Nonhealth hazard --A cross -connection, potential contamination hazard, or other
situation involving any substance that generally will not be a health hazard, but will
constitute a nuisance, or be aesthetically objectionable, if introduced into the public
water supply.
(36) Nontransient noncommunity water system --A public water system that is not a
community water system and regularly serves at least 25 of the same persons at least six
months out of the year.
(37) psi --Pounds per square inch.
(38) Peak hourly demand --In the absence of verified historical data, peak hourly
demand means 1.25 times the maximum daily demand (prorated to an hourly rate) if a
public water supply meets the commission's minimum requirements for elevated storage
capacity and 1.85 times the maximum daily demand (prorated to an hourly rate) if the
system uses pressure tanks or fails to meet the commission's minimum elevated storage
capacity requirement.
(39) Plumbing inspector --Any person employed by a political subdivision for the
purpose of inspecting plumbing work and installations in connection with health and
safety laws and ordinances, who has no financial or advisory interest in any plumbing
company, and who has successfully fulfilled the examinations and requirements of the
Texas State Board of Plumbing Examiners.
(40) Plumbing ordinance --A set of rules governing plumbing practices which is at least
as stringent and comprehensive as one of the following nationally recognized codes:
(A) the International Plumbing Code; or
(B) the Uniform Plumbing Code.
(4 1) Potable water customer service line --The sections of potable water pipe between
the customer's meter and the customer's point of use.
(42) Potable water service line --The section of pipe between the potable water main to
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the customer's side of the water meter. In cases where no customer water meter exists, it
is the section of pipe that is under the ownership and control of the public water system.
(43) Potable water main --A pipe or enclosed constructed conveyance operated by a
public water system which is used for the transmission or distribution of drinking water
to a potable water service line.
(44) Potential contamination hazard --A condition which, by its location, piping or
configuration, has a'reasonable probability of being used incorrectly, through
carelessness, ignorance, or negligence, to create or cause to be created a backflow
condition by which contamination can be introduced into the water supply. Examples of
potential contamination hazards are:
(A) bypass arrangements;
(B) jumper connections;
(C) removable sections or spools; and
(D) swivel or changeover assemblies.
(45) Public drinking water program --Agency staff designated by the executive director
to administer the Safe Drinking Water Act and state statutes related to the regulation of
public drinking water. Any report required to be submitted in this chapter to the
executive director must be submitted to the Texas Commission on Environmental
Quality, Water Supply Division, MC 155, P.O. Box 13087, Austin, Texas 78711-3087.
(46) Public health engineering practices --Requirements in this subchapter or guidelines
promulgated by the executive director.
(47) Public water system --A system for the provision to the public of water for human
consumption through pipes or other constructed conveyances, which includes all uses
described under the definition for drinking water. Such a system must have at least 15
service connections or serve at least 25 individuals at least 60 days out of the year. This
term includes; any collection, treatment, storage, and distribution facilities under the
control of the operator of such system and used primarily in connection with such
system, and any collection or pretreatment storage Cont'd...
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<<Prev Rule Texas Administrative Code Next Rule>>
TITLE 30 ENVIRONMENTAL QUALITY
PART I TEXAS COMMISSION ON ENVIRONMENTAL
QUALITY
CHAPTER290PUBLIC DRINKING WATER
SUBCHAPTER D RULES AND REGULATIONS FOR PUBLIC WATER
SYSTEMS
RULE §290.44 Water Distribution
13MMUTWOi1 . o
(v) Where a new potable waterline crosses a new, pressure rated wastewater main or
lateral, one segment of the waterline pipe shall be centered over the wastewater line such
that the joints of the waterline pipe are equidistant and at least nine feet horizontally
from the center line of the wastewater main or lateral. The potable waterline shall be at
least six inches above the wastewater main or lateral. Whenever possible, the crossing
a)
shall be centered between the joints of the wastewater main or lateral. The wastewater
pipe shall have a minimum pressure rating of at least 150 psi. The wastewater main or
lateral shall be embedded in cement stabilized sand (see clause (vi) of this subparagraph)
for the total length of one pipe segment plus 12 inches beyond the joint on each end.
(vi) Where cement stabilized sand bedding is required, the cement stabilized sand
shall have a minimum of 10% cement per cubic yard of cement stabilized sand mixture,
based on loose dry weight volume (at least 2.5 bags of cement per cubic yard of
mixture). The cement stabilized sand bedding shall be a minimum of six inches above
and four inches below the wastewater main or lateral. The use of brown coloring in
cement stabilized sand for wastewater main or lateral bedding is recommended for the
identification of pressure rated wastewater mains during future construction.
(5) Waterline and wastewater main or lateral manhole or cleanout separation. The
separation distance from a potable waterline to a wastewater main or lateral manhole or
cleanout shall be a minimum of nine feet. Where the nine -foot separation distance
cannot be achieved, the potable waterline shall be encased in a joint of at least 150 psi
pressure class pipe at least 18 feet long and two nominal sizes larger than the new
conveyance. The space around the carrier pipe shall be supported at five-foot intervals
with spacers or be filled to the springline with washed sand. The encasement pipe shall
be centered on the crossing and both ends sealed with cement grout or manufactured
sealant.
(6) Location of fire hydrants. Fire hydrants shall not be installed within nine feet
vertically or horizontally of any wastewater main, wastewater lateral, or wastewater
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service line regardless of construction.
(7) Location of potable or raw water supply or suction lines. Suction. mains to pumping
equipment shall not cross wastewater mains, wastewater laterals, or wastewater service
lines. Raw water supply lines shall not be installed within five feet of any tile or concrete
wastewater main, wastewater lateral, or wastewater service line.
(8) Proximity of septic tank drainfields. Waterlines shall not be installed closer than ten
feet to septic tank drainfields.
(f) Sanitary precautions and disinfection. Sanitary precautions, flushing, disinfection
procedures, and microbiological sampling as prescribed in AWWA standards for
disinfecting water mains shall be followed in laying waterlines.
(1) Pipe shall not be laid in water or placed where it can be flooded with water or
sewage during its storage or installation.
(2) Special precautions must be taken when waterlines are laid under any flowing or
intermittent stream or semipermanent body of water such as marsh, bay, or estuary. In
these cases, the water main shall be installed in a separate watertight pipe encasement
and valves must be provided on each side of the crossing with facilities to allow the
underwater portion of the system to be isolated and tested to determine that there are no
leaks in the underwater line. Alternately, and with the permission of the executive
director, the watertight pipe encasement may be omitted.
(3) New mains shall be thoroughly disinfected in accordance with AWWA Standard
0651 and then flushed and sampled before being placed in service. Samples shall be
collected for microbiological analysis to check the effectiveness of the disinfection
procedure. Sampling shall be repeated if contamination persists. A minimum of one
sample for each 1,000 feet of completed waterline will be required or at the next
available sampling point beyond 1,000 feet as designated by the design engineer.
(g) Interconnections.
(1) Each proposal for a direct connection between public drinking water systems under
separate administrative authority will be considered on an individual basis.
(A) Documents covering the responsibility for sanitary control shall accompany the
submitted planning material.
(B) Each water supply shall be of a safe, potable quality.
(2) Where an interconnection between systems is proposed to provide a second source
of supply for one or both systems, the system being utilized as a second source of supply
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must be capable of supplying a minimum of 0.35 gallons per minute per connection for
the total number of connections in the combined distribution systems.
(h) Backflow, siphonage.
(1) No water connection from any public drinking water supply system shall be
allowed to any residence or establishment where an actual or potential contamination
hazard exists unless the public water facilities are protected from contamination.
(A) At any residence or establishment where an actual or potential contamination
hazard exists, additional protection shall be required at the meter in the form of an air
gap or backflow prevention assembly. The type of backflow prevention assembly
required shall be determined by the specific potential hazard identified in §290.47(1) of
this title (relating to Appendices).
(B) At any residence or establishment where an actual or potential contamination
hazard exists and an adequate internal cross -connection control program is in effect,
backflow protection at the water service entrance or meter is not required.
(i) An adequate internal cross -connection control program shall include an annual
inspection and testing by a certified backflow prevention assembly tester on all backflow
prevention assemblies used for health hazard protection.
(ii) Copies of all such *inspection and test reports must be obtained and kept on file
by the water purveyor.
(iii) It will be the responsibility of the water purveyor to ensure that these
requirements are met.
(2) No water connection from any public drinking water supply system shall be
connected to any condensing, cooling, or industrial process or any other system of
nonpotable usage over which the public water supply system officials do not have
sanitary control, unless the said connection is made in accordance with the requirements
of paragraph (1) of this subsection. Water from such systems cannot be returned to the
potable water supply.
(3) Overhead bulk water dispensing stations must be provided with an air gap between
the filling outlet hose and the receiving tank to protect against back siphonage and cross -
contamination.
(4) All backflow prevention assemblies that are required according to this section and
associated table located in §290.47(i) of this title shall be tested upon installation by a
recognized backflow prevention assembly tester and certified to be operating within
specifications. Backflow prevention assemblies which are installed to provide protection
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against health hazards must also be tested and certified to be operating within
specifications at least annually by a recognized backflow prevention assembly tester.
(A) Recognized backflow prevention assembly testers shall have completed an
executive director approved course on cross -connection control and backflow prevention
assembly testing, pass an examination administered by the executive director, and hold
current professional certification as a backflow prevention assembly tester.
(i) Backflow prevention assembly testers are qualified to test and repair assemblies
on any domestic, commercial, industrial, or irrigation service.
(Ii) Backflow prevention assembly testers may test and repair assemblies on firelines
only if they are permanently employed by an Approved Fireline Contractor. The State
Fire Marshall's office requires that any person performing maintenance on firelines must
be employed by an Approved Fireline Contractor.
(B) Gauges used in the testing of backflow prevention assemblies shall be tested for
accuracy annually in accordance with the University of Southern California's Manual of
Cross -Connection Control or the American Water Works Association Recommended
Practice for Backflow Prevention and Cross -Connection Control (Manual M14). Public
water systems shall require testers to include test gauge serial numbers on "Test and
Maintenance" report forms and ensure testers have gauges tested for accuracy.
(C) A test report must be completed by the recognized backflow prevention assembly
tester for each assembly tested. The signed and dated original must be submitted to the
public water supplier for recordkeeping purposes. Any form which varies from the
format specified in Appendix F located in §290.47(f) of this title must be approved by
the executive director prior to being placed in use.
(5) The use of a backflow prevention assembly at the service connection shall be
considered as additional backflow protection and shall not negate the use of backflow
protection on internal hazards as outlined and enforced by local plumbing codes.
(6) At any residence or establishment where there is no actual or potential
contamination hazard, a backflow prevention assembly is not required.
(i) Water hauling. When drinking water is distributed by tank truck or trailer, it must be
accomplished in the following manner.
(1) Water shall be obtained from an approved source.
(2) The equipment used to haul the water must be approved by the executive director
and must be constructed as follows.
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(A) The tank truck or trailer shall be used for transporting drinking water only and
shall be labeled "Drinking Water." Tanks which have been used previously for purposes
other than transporting potable liquids shall not be used for hauling drinking water.
(B) The tank shall be watertight and of an approved material which is impervious and
easily cleaned and disinfected. Any paint or coating and any plastic or fiberglass
materials used as contact surfaces must be approved by the United States Environmental
Protection Agency, the United States Food and Drug Administration, or the NSF.
Effective January 1, 1993, any newly installed surfaces shall conform to ANSI/NSF
Standard 61 and must be certified by an organization accredited by ANSI.
(C) The tank shall have a manhole and a manhole cover which overlaps the raised
manhole opening by a minimum of two inches and terminates in a downward direction.
The cover shall fit firmly on the manhole opening and shall be kept locked.
(D) The tank shall have a vent which is faced downward and located to minimize the
possibility of drawing contaminants into the stored water. The vent must be screened
with 16 -mesh or finer corrosion -resistant material.
(E) Connections for filling and emptying the tank shall be properly protected to
prevent the possible entrance of contamination. These openings must be provided with
caps and keeper chains.
(F) A drain shall be provided which will completely empty the tank for cleaning or
repairs.
(G) When a pump is used to transfer the water from the tank, the pump shall be
permanently mounted with a permanent connection to the tank. The discharge side of the
pump shall be properly protected between uses by a protective cap and keeper chain.
(H) Hoses used for the transfer of drinking water to and from the tank shall be used
only for that purpose and labeled for drinking water only. The hoses shall conform to
ANSI/NSF Standard 61 and must be certified by an entity recognized by the
commission. Hoses and related appurtenances must be cleaned and disinfected on a
regular basis during prolonged use or before start-up during intermittent use. Hoses must
be properly stored between uses and must be provided with caps and keeper chains or
have the ends connected together.
(1) The tank shall be disinfected monthly and at any time that contamination is
suspected.
(J) At least one sample per month from each tank shall be collected and submitted for
microbiological analysis to one of the commission's approved laboratories for each
month of operation.
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(K) A minimum free chlorine residual of 0.5 mg/L or, if chloramines are used as the
primary disinfectant, a chloramine residual of 1.0 mg/L (measured as total chlorine)
shall be maintained in the water being hauled. Chlorine or chlorine containing
compounds may be added on a "batch" basis to maintain the required residual.
(L) Operational records detailing the amount of water hauled, purchases,
microbiological sampling results, chlorine residual readings, dates of disinfection, and
source of water shall be maintained.
Source Note: The provisions of this §290.44 adopted to be effective October 1, 1992, 17
TexReg 6455; amended to be effective November 3, 1995, 20 TexReg 8620; amended to
be effective March 3, 1997, 22 TexReg 1809; amended to be effective February 4, 1999,
24 TexReg 731; amended to be effective September 13, 2000, 25 TexReg 8880;
amended to be effective May 16, 2002, 27 TexReg 4127; amended to be effective
February 19, 2004, 29 TexReg 1373
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Don Ellison - Re: Ross Bannisters rainwater harvesting Page 1
From: Nathan Loftice
To: Albrecht, Warren; Robertson, John; White, Frank
Date: 9/4/2007 11:43:19 AM
Subject: Re: Ross Bannister's rainwater harvesting
Regarding the consumption of rainwater....
I reviewed his treatment mechanisms. I recommend the water be tested by the private homeowner to
ensure safe consumption. He are a few things to consider:
*Evaluate what the proposed systems actually treat.
*What about nonconventional pollutants such as Volatile Organic Compounds. As the rainwater falls it
could pick up pollutants.
*As the rain water runs off it could pick up pollutants. What is rainwater running off of, metal roof? What
about metals in the rainwater (RCRA 8 metals)?
Just some thougths.
Nathan Joe Loftice - Environmental Manager
Public Works - Environmental Services Division
City of Grapevine, Texas
(817) 410-3330
>>> John Robertson 9/4/2007 11:15 AM >>>
Frank, Warren, Nathan, Matt and Stan:
As you may or may not be aware of, Ross Bannister is building a house on Ball Street, across from the
botanical gardens. He is also installing a rainwater harvesting system for use as potable water.
He is also tying into the City system so as to get "make-up" water during dry spells. The tie in to the City
system will have a backflow preventor as well as a 4" air gap between the City service line and his water
storage tank.
Don Ellison has provided me with copies of several items pertaining to this system including specs and
summary for his house, The Texas Manual on Rainwater Harvesting, and the Report to the 80th
Legislature for Rainwater Harvesting Potential and Guidelines for Texas. Within these reports, it
discusses various TCEQ regulations, etc... all of which we appear to be adhering to for this system as far
as the service connection to this system. However, any of you may be aware of other issues that need to
be addressed.
There are other items, including routine testing of the harvested water that are recommended at various
time intervals (3 months for potable), that would most likely fall under the private side... This may fall under
the responsibility of the property owner, to obtain for their own health... and since it will not be directly
connected to the City system, I do not believe this would fall under Public Work's need to enforce nor
obtain records for. All the filtering and UV purifiers are on the private side for this "harvested" water.
I'll put this information in a file up near the Public Works secretaries, but if you need a copy, or would like
to see it for your information, please let me know.
thanks,
John
John D. Robertson, P.E.
Civil Engineer
Don Ellison - Re Ross Bannister's Rainwater Harvesting System Page 1
From: Scott Williams
To: Don Ellison; Matt Singleton; Nathan Loftice; Scott Dyer; Stan Laster
Date: 9/17/2007 11:20:07 AM
Subject: Re: Ross Bannister's Rainwater Harvesting System
They have an air gap, so no double check is required. They comply with the plumbing code. If you have no
concerns, we'll issue the permit. FYI- The annual testing is required only on 'high hazard' installations.
>>> Matt Singleton 9/17/2007 10:11 AM >>>
Your code can require a double check valve be placed on the downstream side of the meter to ensure
additional protection. Additionally the code requires that the double check be inspected and certified
operational by a certified inspector annually. If you are concerned about future cross contamination then I
would recommend that this be required.
Matt Singleton
Director of Public Works
City of Grapevine, TX
>>> Scott Williams 9/17/2007 10:02 AM >>>
17Sept2007
I have reviewed the proposed drawings, and am confident that the Public Water Supply is protected, as
there is a physical air gap between the water supply and the cistern. However, there is absolutely no way
to verify the quality of the potable water to the inhabitants of the house, nor is there any assurance that a
physical connection won't be made in the future. This may be a conscious decision made by the Bannister
family, but I would have concerns about protecting future buyers of the home.
As the PWS is protected, I don't have anything in the Plumbing Code to prevent it. Hopefully there is
something in your ordinances that will let us keep this from happening. I have no problem with the use of
such system for non -potable water, but it is potentially dangerous to use for potable systems. Don, please
make sure a copy of this email is put in the permanent file for the property.
J. Scott Williams
Director of Development
City of Grapevine, Texas
(817) 410-3158
Rainwater Harvesting System Overview for
Bannister Dome, Grapevine, TX.-
Specs for Rainwater Harvesting system per Texas Rainwater Harvesting Committee
Guidelines:
Storage:
■ Pioneer Water Tank — 9,927 gallons
■ 15' 5" diameter X 7' 3" high
■ NSF Approved for potable water storage
Conveyance:
■ Metal Roof
■ Gutters w/ gutter protection
■ 3" to 6" Schedule 40 PVC
Filtration:
Delivery:
Other:
■ Gutter Screens
■ WISY first flush- diverter
■ Sediment — Mosquito Screens on all inlets and outlets.
■ Pura Pre -pump 20 micron sediment filter
■ Pura UV -20 3 stage filter for potable use
■ Grundfos MQ 1 hp on -demand pump
■ Backflow at Street
■ 4" vapor gap at tank inlet
■ Mosquito Prevention with mesh screens on all inlets and outlets.
Rainwater Harvesting Potential and Guidelines for Texas
Report to the 80th Legislature
Submitted by
Texas Rainwater Harvesting Evaluation Committee
Texas Water Development Board
Texas Commission on Environmental Quality
Texas Department of State Health Services
Texas Section of the American Water Works Association
Conservation and Reuse Division
Published by
Texas Water Development Board
Austin, Texas
November 2006
Table of Contents
ExecutiveSummary ......................................................................................1
Key Findings and Recommendations..........................................................2
1. Introduction............................................................................................... 5
2. The Potential for Rainwater Harvesting in Texas..................................9
3. Minimum Water Quality Guidelines for Indoor Use of Rainwater ....... 17
4. Treatment Methods for Indoor Use of Rainwater.................................23
5. Using Rainwater Harvesting Systems in Conjunction with
Public Water Systems............................................................................29
6. Recommendations for Promoting Rainwater Harvesting in Texas .....35
References...................................................................................................37
Appendix
Other Suggestions for Promoting Rainwater Harvesting...................38
Acknowledgements..................................................................................... 39
Rainwater Harvesting Evaluation Committee Members,
Alternate members, and Resource Persons........................................41
Disclaimer - The mention of brand names or products in this report does not
constitute an endorsement of those products by the Texas Rainwater
Harvesting Evaluation Committee or by the State of Texas.
Executive Summary
The Texas Water Development Board (TWDB) established the Texas Rainwater
Harvesting Evaluation Committee pursuant to the passage of House Bill 2430 by
the 79th Texas Legislature in 2005. In accordance with House Bill 2430,
membership of the Texas Rainwater Harvesting Evaluation Committee consists
of representatives from the TWDB, the Texas Commission on Environmental
Quality, the Texas Department of State Health Services, and the Texas Section
of the American Water Works Association Conservation and Reuse Division.
House Bill 2430 directs the Texas Rainwater Harvesting Evaluation Committee to
evaluate the potential for rainwater harvesting in Texas and to recommend
(a) minimum water quality guidelines and standards for potable and non -
potable indoor uses of rainwater;
(b) treatment methods for potable and non -potable indoor uses of rainwater;
(c) ways, such as dual plumbing systems, to use rainwater harvesting
systems in conjunction with existing municipal water systems; and
(d) ways that the state can further promote rainwater harvesting.
In addition, House Bill 2430 directs the Texas Commission on Environmental
Quality to establish recommended standards for the domestic use of harvested
rainwater, including health and safety standards. It also directs them to develop
standards for collection methods for harvesting rainwater intended for drinking,
cooking, and bathing. The legislation requires the Texas Commission on
Environmental Quality to adopt these recommended standards by December 1,
2006.
The Texas Rainwater Harvesting Evaluation Committee has concluded its
evaluation of the potential for rainwater harvesting in Texas, has formulated its
recommendations regarding minimum water quality guidelines, standards, and
methods of treatment for the safe use of water for indoor purposes, ways in
which to incorporate rainwater harvesting with existing public water systems, and
the state's role in promoting rainwater harvesting.
This report represents the fulfillment of the committee's obligation under House
Bill 2430 to submit its evaluation and associated recommendations in a report to
the Texas Lieutenant Governor and Speaker of the Texas House of
Representatives by December 1, 2006.
In this report, the Texas Rainwater Harvesting Evaluation Committee presents a
narrative discussion, associated maps, and other illustrations relating to the
potential benefits and advantages that may be derived from rainwater harvesting.
In addition, the committee respectfully submits the following key findings and 10
key recommendations:
Key Findings and Recommendations
Potential for Rainwater Harvesting in Texas
Key Finding
There is a significant untapped potential to generate additional water
supplies in Texas through rainwater harvesting, particularly in urban
and suburban areas.
In most areas of the state, rainfall is sufficient to make rainwater harvesting a
reliable and economical source of water even during short-term droughts.
Because rainfall is generally harvested in the same location where it will be
used, the need for complex and costly distribution systems is eliminated. An
estimated 2 billion gallons of water could be generated annually in a large
metropolitan area the size of Dallas if 10 percent of the roof area were used
to harvest rainwater. Approximately 38 billion gallons of water would be
conserved annually if 10 percent of the roof area in Texas could be used for
rainwater harvesting.
• Recommendations
The legislature should consider expanding the state's role in promoting
rainwater harvesting by:
Directing new state facilities with 10, 000 square feet or greater in roof
area (and smaller facilities, when feasible), to incorporate rainwater
harvesting systems into their design and construction. Harvested
rainwater at these locations may be used for restroom facilities and/or
landscape watering.
2. Developing incentive programs to encourage the incorporation of
rainwater harvesting systems into the design and construction of new
residential, commercial, and industrial facilities in the state.
3. Considering a biennial appropriation of $500,000 to the Texas Water
Development Board to help provide matching grants for rainwater
harvesting demonstration projects across the state.
K
Guidelines, Standards, and Regulations
• Key Finding:
With the application of appropriate water quality standards, treatment
methods, and cross -connection safeguards, rainwater harvesting
systems can be used in conjunction with public water systems.
Harvested rainwater may be the only source of water supply for many rural
and remote households where no other water supply is available. In urban
and suburban environments, rainwater harvesting could help public water
systems reduce peak demands and help delay the need for expanding water
treatment plants. Rainwater harvesting can reduce storm water runoff, non -
point source pollution, and erosion in urban environments. Rainwater is
valued for its purity and softness and is generally superior for landscape
purposes to most conventional public water supplies. Rainwater harvesting
can be used for both indoor and outdoor purposes in residential, commercial,
and industrial applications.
• Recommendations
The legislature should consider.-
4.
onsider.
4. Directing the Texas Commission on Environmental Quality and other
state agencies to continue to exempt homes that use rainwater
harvesting as their sole source of water supply from various water
quality regulations that may be required of public water systems.
Guidelines are provided in this report to assist homeowners in
improving and maintaining the quality of rainwater for potable and non -
potable indoor uses.
5. Directing the Texas Commission on Environmental Quality and other
state agencies to require those facilities that use both public water
supplies and harvested rainwater for indoor purposes to have
appropriate cross -connection safeguards, and to use the rainwater
only for non -potable indoor purposes.
6. Appropriating $250,000 to the Texas Department of State Health
Services to conduct a public health epidemiologic field and laboratory
study to assess the pre- and post-treatment water quality from different
types of rainwater harvesting systems in Texas, and to submit a report
of findings to the next session of the legislature.
7. Directing Texas cities to enact ordinances requiring their permitting
staff and building inspectors to become more knowledgeable about
rainwater harvesting systems, and allow such systems in homes and
other buildings, when properly designed.
3
Training Education, and Certification
• Key Finding
There is a need to develop training and educational materials on
rainwater harvesting to help design appropriate systems and to realize
the full potential of rainwater harvesting in Texas.
Successful and widespread integration of rainwater harvesting systems with
public water systems requires a commitment on the part of state and local
governments to develop professional programs and opportunities for
education, training, and certification on rainwater harvesting systems. In
Texas, there are currently no licenses or certifications required to design,
install, or maintain a rainwater harvesting system. In addition, the current
training conducted by the Texas State Board of Plumbing Examiners for
licensed plumbers and water utility operators does not include any information
regarding rainwater harvesting systems.
• Recommendations
To help improve the professional service capabilities of rainwater
harvesting consultants, contractors, and local governments, the
legislature should consider.
8. Directing a cooperative effort by the Texas Commission on
Environmental Quality and the Texas State Board of Plumbing
Examiners to develop a certification program for rainwater harvesting
system installers, and provide continuing education programs.
9. Directing Texas Cooperative Extension to expand their training and
information dissemination programs to include rainwater harvesting for
indoor uses.
10. Encouraging Texas institutions of higher education and technical
colleges to develop curricula and provide instruction on rainwater
harvesting technology.
Chapter 1 - Introduction
The population in Texas is expected to more than double between the years
2000 and 2060, growing from almost 21 million to about 46 million. That
population growth will result in twice the municipal water demand, which is
projected to increase from about 4 million acre-feet per year in 2000 to 8.2 million
acre-feet per year in 2060. However, during that same time period, the total
water supply in Texas is projected to decrease by 3.2 million acre-feet per year
from 17.8 million acre-feet in 2010 to about 14.6 million acre-feet in 2060 due to
various factors, such as reservoir sedimentation and reduced aquifer yields.
Faced with a growing population and a diminishing water supply, Texas will need
to develop new water supplies and encourage alternative technologies such as
rainwater harvesting, to supplement available water sources.
The Texas Legislature and state water agencies have promoted the use of
rainwater harvesting through several actions in the past (Krishna, 2005). In
1993, Proposition 2 was passed in Texas, providing property tax relief to
commercial and industrial facilities that use rainwater harvesting and pollution
control measures. Senate Bill 2, passed in 2001 by the 77th Legislature, allows
local taxing entities the authority to exempt all or part of the assessed value of
the property on which water conservation modifications, such as rainwater
harvesting, are made. Senate Bill 2 also provides sales tax exemptions for
rainwater harvesting equipment. House Bill 645, passed in 2003 by the 78th
Legislature, prevents homeowners' associations from implementing new
covenants banning outdoor water conservation measures, such as rainwater
harvesting. A rainwater harvesting and water recycling task force submitted a
report to the Texas Residential Construction Commission in 2005 (TRCC, 2005)
recommending development of resource information and encouraging builders to
incorporate rainwater harvesting systems. This report provides the needed
resource information and water quality guidelines for rainwater harvesting
systems.
Rainwater and snowmelt are the primary sources for all fresh water on the
planet. The practice of collecting runoff from rainfall events can be classified into
two broad categories: land-based and roof -based. Land-based rainwater
harvesting occurs when runoff from land surfaces is collected in furrow dikes,
ponds, tanks and reservoirs. As its name implies, roof -based rainwater
harvesting refers to collecting rainwater runoff from roof surfaces. Roof -based
rainwater harvesting results in a much cleaner source of water and provides
water that can be used both for landscape watering and for indoor purposes.
Roof -based rainwater harvesting is the focus of this report.
Before the advent of large-scale public water systems, capturing rain in cisterns
for residential and various commercial purposes had been a relatively common
practice in Texas in the 19th century. Since the mid-1990s, there has been
renewed interest in rainwater harvesting as a low-cost technology that produces
5
water of relatively good quality. In Central Texas alone, it is estimated that at
least 500 residential rainwater harvesting systems have been installed in the past
10 years. Homes in remote areas with no access to other sources of water
supply depend on rainwater for all their needs. In addition to residential use,
there are many examples of rainwater harvesting systems being used in
commercial and industrial applications (TWDB, 2005). Public facilities, such as
schools and community centers have started harvesting rainwater to conserve
water supplies. The City of Austin has encouraged the use of rainwater as a
supplemental source of water for residential and other applications.
Surveys of various state agencies suggest that there may be as many as
100,000 rainwater harvesting systems in use in the United States (Lye, 2003).
Portland, Oregon, and the State of Washington have developed guidelines for
designing and installing rainwater harvesting systems. Santa Fe, New Mexico
requires the installation of rainwater harvesting systems on all new residential
structures greater than 2,500 square feet. Tucson, Arizona, has instituted
requirements for rainwater harvesting in its land use code to provide
supplemental water for on-site irrigation as well as for floodplain and erosion
control. In Hawaii, up to 60,000 people depend on rainwater harvesting systems
for their water needs (Macomber, 2001).
Rainwater harvesting systems have also been popular in other countries. Several
countries in Western Europe use them to conserve municipal water supplies, as
does Australia. Some states in India have made rainwater harvesting mandatory
in all new buildings. Rainwater harvesting is required by law in the U.S. Virgin
Islands and many other Caribbean islands
There are numerous potential benefits and advantages from rainwater harvesting
(Krishna, 2003). Rainwater harvesting systems can
• provide a source of free water—the only costs would be for storage,
treatment and use;
• provide water if there is no other source of water;
• augment or replace limited quantities of groundwater;
• provide good -quality water if groundwater quality is unacceptable;
• provide water if tap charges are too high for water supply connection;
• reduce storm water runoff;
• reduce non -point source pollution;
• reduce erosion in urban environments;
• provide water that is naturally soft (no need for water softeners);
• provide water that is pH neutral/slightly acidic;
2
• provide water that is sodium -free, important for those on low -sodium diets;
• provide good quality water for landscape irrigation;
• provide water for non -potable indoor uses;
• provide safe water for human consumption, after appropriate treatment;
• help utilities in reducing peak demands in the summer;
• help utilities in delaying the expansion of water treatment plants;
• provide water for cooling and air-conditioning plants;
• reduce the demands on groundwater;
• provide water for fire protection; and
• save money for the consumer in utility bills.
Rainwater harvesting also provides several additional benefits. It can reduce
scaling build-up in hot water heaters, plumbing, faucets, and showerheads.
Rainwater requires less soap and detergent than most public water supplies
because of its natural softness. In particular, use of rainwater can be valuable
for the hotel industry, helping them reduce their use of municipal water
supplies and the amount of detergents used for their daily laundry.
7
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Chapter 2 - The Potential for Rainwater Harvesting in
Texas
Rainwater harvesting has considerable potential as a source of alternate water
supply in Texas if the systems that collect the rainwater are properly designed
and implemented. The amount of rainwater that can be collected is a function of
roof area and rainfall. In order to determine the potential benefits from rainwater
harvesting in Texas, statewide rainfall data and roof area information from nine
representative cities across the state were obtained. The average annual rainfall
in Texas is approximately 28 inches, and the total roof area in the state is
estimated to be approximately 22.5 billion square feet.
According to the Texas Rainwater Harvesting Evaluation Committee's analysis,
approximately 2 billion gallons of water could be generated annually in a large
metropolitan area the size of Dallas if 10 percent of its roof area were used to
harvest rainwater. If 10 percent of all the roof area in the state were used to
harvest rainwater, an estimated 38 billion gallons of water could be generated
annually in Texas. This is equivalent to producing about 104 million gallons per
day of new water. In general, for every 1 percent of total roof area in the state
used to harvest rainwater, approximately 11,650 acre-feet per year of additional
water could be generated.
The Texas Rainwater Harvesting Evaluation Committee also estimated how
much water could be collected from just residential buildings (homes and
apartments) by examining census data and other information on housing units.
The total residential roof area in the state was estimated at 15.7 billion square
feet. By collecting rainwater from 10 percent of the residential roof area in the
state, an estimated 27 billion gallons of water could be conserved.
In addition to its potential to generate considerable quantities of water, rainwater
harvesting results in a process of collecting water that is decentralized and
therefore, relatively less vulnerable than conventional public water supplies to
natural disasters or terrorism. Another advantage of rainwater harvesting is that
its systems are generally cost -competitive with well drilling and it provides water
that is naturally soft, eliminating the need for water softeners. In some cases,
rainwater harvesting is less expensive than the costs associated with obtaining a
tap connection from water supply corporations.
Rainwater Harvesting Feasibility in Texas
With respect to the feasibility of using rainwater harvesting systems in Texas, it is
important to realize that rainwater harvesting may be the only option in many
rural areas where there is no other source of water supply. Also, rainwater can
be used as a sole source of water supply or in conjunction with other water
sources such as surface water or groundwater. The Texas Rainwater Harvesting
Evaluation Committee examined to what degree rainfall patterns in different
regions of the state affect the viability of this alternative water supply option. After
reviewing rainfall and runoff data, and the evidence presented by a number of
individuals who have successfully practiced rainwater harvesting in the state, the
Texas Rainwater Harvesting Evaluation Committee has concluded that rainwater
harvesting systems, if properly designed, can provide adequate water supplies in
most regions of the state even during periods of short-term drought. It is,
however, necessary to practice water conservation to ensure the success of
rainwater harvesting, especially when it is the sole source of watersupply.
According to the Handbook of Water Use and Conservation (Vickers, 2001), the
average indoor water use in a water -conserving home in the United States is
45.2 gallons per capita per day; clothes washers and toilets consume about 40
percent of this amount (approximately 18 gallons per capita per day). However,
most homeowners who rely solely on rainwater harvesting systems routinely use
between 30-40 gallons per capita per day for indoor purposes, that includes
about 14 gallons per capita per day for clothes washers and toilets. This level of
indoor water consumption is based on the use of water -conserving showerheads
and faucets and high -efficiency flush toilets, clothes washers, and dishwashers.
The maps and discussion in this chapter are intended to provide information
regarding the suitability of rainwater harvesting technology in various rainfall
zones throughout the state. Annual rainfall in Texas ranges from less than 10
inches in West Texas to more than 50 inches in East Texas (Figure 1). In most
areas of the state, rainy seasons occur during the months of April -June and
again in September -October, with a relatively dry period during the interim
months of July and August.
In general, rainwater harvesting will be successful if sufficient rainwater can be
captured and stored to satisfy needs during those dry periods, and dry periods
increase from 50 days in East Texas to 120 days in West Texas (Figure 2). In
other words, rainwater harvesting systems would need to provide adequate water
storage to meet the needs during those relatively dry periods. In Central Texas,
for example, that would mean water storage for an 80 -day period.
Assuming a rainfall collection efficiency of 80 percent, a rainwater harvesting
system using 2,000 square feet of roof area will generate approximately 1,000
gallons of water for every inch of rainfall. This mathematical relationship holds
true in all regions of Texas. For example, in the Austin area (south central
Texas) where the average annual rainfall is 33 inches, one would expect to
collect approximately 33,000 gallons of rainwater annually from a 2,000 square
foot roof (Figure 3). In the San Angelo area (west central Texas), where the
average annual rainfall is 19 inches, one would expect to collect approximately
19,000 gallons of rainwater annually from a 2000 square foot roof. The amount of
water that can be collected from a typical 2,000 square foot roof generally ranges
10
from about 12,000 gallons per year in areas of West Texas to about 60,000
gallons per year in areas of East Texas.
To determine the rainwater harvesting potential at any location, the following
equation may be used: Annual Rainwater Harvesting Potential (Gallons) =
Average annual rainfall (in inches) * 0.62 * 0.80 * Collection area (in square feet).
If the average annual rainfall is not known, a location's longitude could be used to
estimate the average annual rainfall as shown below.
The potential for rainwater harvesting as a water resource was estimated through
a regression analysis that was performed on historic rainfall for 13 major Texas
cities geographically scattered across the state. The following equation can be
used by water resource planners to estimate the average annual rainfall for any
particular community in Texas, using longitude. Average annual rainfall (in
inches) = 352.2 - (3.27 * Longitude).
The Texas Rainwater Harvesting Evaluation Committee is of the opinion that
rainwater harvesting technology is applicable to all areas of Texas, however, its
greatest potential for indoor uses may be in the yellow, green and blue zones
that range in average annual rainfall from about 20 inches to over 50 inches.
Together, these rainfall zones encompass approximately 75 percent of the
state's total area. To meet household needs in the red zone, a larger surface
area may be needed for rainwater collection, along with a back-up or alternate
source of water supply to cover extended dry periods.
Potential Impact of Rainwater Harvesting on Streamflow
To examine the potential impact of rainwater harvesting on streamflow in the
state, the Texas Rainwater Harvesting Evaluation Committee determined the
amount of rainfall that would be captured if 10 percent of the total roof area in the
state were equipped with rainwater harvesting systems. That value was
compared with total rainfall and mean annual streamflow discharged into the Gulf
of Mexico by the state's rivers and streams.
Assuming a statewide average precipitation of 28 inches per year, the Texas
Rainwater Harvesting Evaluation Committee determined that capturing rainfall on
10 percent of the total roof area in the state over the course of one year would
generate approximately 120,000 acre-feet of water. The committee compared
this value to the 396 million acre-feet of water resulting from the 28 inches of
rainfall over the entire state and found that the rainfall intercepted by rainwater
harvesting amounted to only 0.03 percent of the statewide rainfall total.
The combined mean streamflow discharged by the state's rivers and streams into
the Gulf of Mexico totals approximately 40 million acre-feet per year. The
committee compared this value to the estimated 120,000 acre-feet of water
11
conserved annually by capturing rainfall on 10 percent of the total roof area in the
state, and determined that the rainwater captured represents only 0.3 percent of
total streamflow entering the Gulf of Mexico via our state's rivers and streams.
Therefore, if a goal of capturing up to 10 percent of the total roof area in the state
via rainwater harvesting is achieved, it is reasonable to conclude that this level of
rainfall diversion would have little or no impact on total streamflow in the state.
Rainwater harvesting may even provide a measure of relief from demands
placed on surface waters in the state, ultimately increasing overall streamflow.
12
Rainfall in inches per year
Acknowledgement of the following agencies In products derived from these data:
Natural Resources Conservation Service (NRCS) Mater and Climate Center, NRCS
National Cartography and Geospatial Cemer (NCGC), PRISM Model, and the Oregon
Climate Service at Oregon State University.
0 50
100
150
2w
Miles
48
i .fie 36 044
32 u vet
28 4o-
s
A i
� o
ron..
,
24 Map rpaedwMaMx�res.zoos
T B- GIs .app q CooN—r
Figure 1. Average annual rainfall in Texas (in inches).
13
Maximum Number of Consecutive Days
Without Rainfall in Texas
�m
60
0 30 100 Iso 700
Miles
Figure 2. A map of Texas with isolines showing the maximum number of
consecutive days without rainfall (Krishna, 2003; TWDB, 2005).
14
Average Annual Runoff from 2,000 square feet of Roof Area
24
12
40 .. 48
" 32 UO
Runoff in Thousands of Gallons.28 Runoff computed by Hari J. Krishna
Map created by Mark Hayes
24 -%r- 7UVDB - 2006
50 100
150
700
Miles
Figure 3. Map of Texas showing isolines of average annual runoff (in thousands
of gallons) that can be expected from 2,000 square feet of roof area.
15
Conclusions:
• Rainwater harvesting is the only source of water supply in many rural
communities where there is no other source of water.
• Under average rainfall conditions, a considerable amount of water
(approximately 120,000 acre-feet per year) can be generated through
rainwater harvesting systems from just 10 percent of the roof area in
Texas.
• Rainwater harvesting provides a decentralized system of water supply that
would be less vulnerable to natural disasters or terrorism.
• A color -coded map of Texas has been specifically developed for this
report which shows that the average annual roof runoff can range from
about 12,000 gallons in West Texas to about 60,000 gallons in East Texas
from a typical 2,000 square foot roof.
• Rainwater can be used for indoor and/or outdoor purposes, in homes, and
in commercial and industrial facilities.
• Rainwater can be used as a sole source of water supply or in conjunction
with other sources of water supply such as groundwater and surface
water.
• Evidence has been presented to the Texas Rainwater Harvesting
Evaluation Committee to indicate that rainwater harvesting systems are
practical and cost -competitive with well water systems, and also in relation
to the costs associated with obtaining a tap connection from water supply
corporations in some areas.
The quantity of water that could be collected through rainwater harvesting
would constitute less than 1 percent of the state's streamflow and will
therefore have little impact on the water that flows in the rivers and
streams of the state.
0
Chapter 3 - Minimum Water Quality Guidelines for Indoor
Use of Rainwater
Although rainwater is one of the purest forms of water, it is still necessary to
establish minimum water quality guidelines for its use, because the water can
become contaminated during the rain harvesting process. House Bill 2430
requires the Texas Commission on Environmental Quality to establish
"recommended standards" related to the domestic use of harvested rainwater.
Since these are to be recommended standards and not regulations, the Texas
Commission on Environmental Quality will adopt these standards in the form of
guidelines, and they will be published as regulatory guidance documents. This
chapter will discuss water quality considerations and establish coliform guidelines
for the safe use of rainwater.
From a regulatory standpoint, the Texas Commission on Environmental Quality
considers rainwater harvesting systems that provide water to individual homes to
be similar to the regulatory status of private domestic wells that serve individual
homes in Texas. There are no statutes or regulations at the state or federal level
currently that regulate the potable and non -potable indoor uses of domestic well
water systems. Therefore, the Texas Commission on Environmental Quality will
also not regulate the potable and non -potable indoor use of rainwater systems in
individual homes if those homes are not connected to any public water systems.
Minimum Water Quality Guidelines for Non -Potable Indoor Use of
Rainwater (Residential and Commercial Facilities):
Typical non -potable indoor uses for rainwater would include washing clothes and
flushing toilets. If a public water system is to be used as a back-up source of
water, the non -potable rainwater must not be allowed to contaminate the public
water supply. This can be accomplished by providing an air gap in the storage
tank for the backup water supply. Alternately, a mechanical device referred to as
a reduced pressure zone back flow preventer must be used. Chapter 5 will
include a further discussion of the conjunctive use of rainwater with public water
systems.
Even though bacterial contamination of water for indoor non -potable use is not as
critical as that used for potable purposes, total coliform and fecal coliform
sampling can be used to evaluate a general level of acceptable microbial
contamination for non -potable water. The acceptable level of total coliform for
non -potable water should be less than 500 cfu/100 ml, and fecal coliform levels
should be less than 100 cfu/100ml. Testing is recommended on an annual basis
(Lye, 2005).
ifi
Minimum Water Quality Guidelines for Potable Use of Rainwater
(Residential):
In addition to drinking water, potable uses for harvested rainwater typically
include shower or bath as well as kitchen uses, such as dishwashing and food
preparation. Rainwater collected from roofs is not subject to the same level of
contamination as surface water such as streams, rivers and lakes, but if it is to be
used for potable purposes, it needs to be both microbiologically and chemically
safe.
Rainwater for potable use should meet a higher level of requirements for turbidity
and microbiology than non -potable rainwater. The presence of suspended
material in water, such as finely divided organic material, plankton, clay, silt, and
other inorganic material, is indicated through turbidity, measured as NTU
(nephelometric turbidity units). High turbidity also interferes with disinfection.
Turbidity in water from surface water sources is currently regulated by the Safe
Drinking Water Act to be less than 1 NTU (AWWA, 2006). This same level of
turbidity is recommended for rainwater used for potable purposes in private
homes.
Filtration is essential to control particulates, and homeowners must be diligent in
cleaning and changing their filters to ensure that turbidity levels are controlled.
The filters need to be replaced regularly in accordance with manufacturers'
recommendations. A further discussion of filtration and other treatment
requirements will be presented in Chapter 4.
It is also important that the water be free of microbiological contaminants. Thus,
both the total coliform and fecal coliform levels in treated rainwater for potable
use should be maintained at zero. In addition, there should be no protozoan
cysts (such as Giardia Lamblia and Cryptosporidium) and no viruses. Testing for
total coliform and fecal coliform or e.coli at least on a quarterly basis will help
monitor the water quality.
Minimum Water Quality Guidelines for Potable Use of Rainwater
(Community and Public Water Systems)
State and federal drinking water regulations that apply to public water systems
establish the "gold standard" for ensuring the safety of drinking water. A public
water system is one that is defined as a water system that serves fifteen
connections or 25 people for at least 60 days of the year. These are further
broken down into community and non -community water systems. Community
water systems are those that serve residential connections, whereas non-
community water systems serve nonresidential connections, such as businesses,
restaurants, highway rest areas, parks, churches, and schools.
18
It is necessary that rainwater for potable use in public water systems meet the
same health protection goals as other sources of water used in public water
systems. Potable rainwater systems that meet the definition of a public water
system will be required to meet all applicable public water system regulations set
by the Texas Commission on Environmental Quality, under Title 30, Texas
Administrative Code, Chapter 290.
Federal and state standards have established a turbidity level of 0.3 NTU as the
standard for potable water used in public water systems. The Texas Commission
on Environmental Quality requires filtration to provide this same level of turbidity
if the rainwater is used for public water supply. Turbidity needs to be monitored at
least on a quarterly basis. Monthly monitoring of total coliforms and fecal
coliforms is required to ensure that they are both absent in public water supplies.
In addition, there should be no protozoan cysts (such as Giardia Lamblia and
Cryptosporidium) and no viruses.
The regulations that apply to public water systems require extensive monitoring
and require construction and operation practices as prescribed under the
regulations. Those same standards would apply to any rainwater harvesting
operation that provides water to a public water system. However, because of the
unique characteristics of rainwater, alternate methods for meeting the filtration
and disinfection requirements are acceptable, but must be approved under the
Texas Commission on Environmental Quality's innovative/alternate treatment
provisions under Title 30, Texas Administrative Code, Chapter 290.42(g).
Table 1 provides a summary of the minimum microbiological guidelines for indoor
use of rainwater, both for private homes and for public water systems. In addition
to testing for microbiological indicators, users of rainwater for potable purposes
may have their water tested for possible chemical contaminants too, at many
water testing laboratories.
Water Testing Laboratories
Water samples can be routinely analyzed at many health department, water
utility, and river authority laboratories. However, not all of these entities perform
analyses which enumerate the level of coliforms. Many labs only analyze for
presence or absence of total coliforms and fecal coliforms. Laboratories that are
accredited by the Texas Commission on Environmental Quality can be found on
their website at:
http://www.tceg.state.tx.us/compliance/compliance support/aa/env lab accredit
ation.html
19
Table 1. Minimum Water Quality Guidelines for Indoor Use of Rainwater
Category of Use
Rainwater Quality for
Non -Potable Indoor Use
Rainwater Quality for
Potable Uses
Single Family
Total Coliforms
Total Coliform - 0
Households
<500 cfu / 100 ml
Fecal Coliform - 0
Protozoan Cysts — 0
Fecal Coliforms
Viruses — 0
<100 cfu / 100 ml
Turbidity < 1 NTLI
Water testing
Water testing
recommended annually
recommended every 3
months
Community or Public
Total Coliforms
Total Coliform - 0
Water System
<500 cfu/100 ml
Fecal Coliform - 0
Protozoan Cysts - 0
Fecal Coliforms
Viruses - 0
<100 cfu/100 ml
Turbidity < 0.3 NTLI
Water testing
Water testing required
recommended annually
monthly
In addition, the water
must meet all other public
water supply regulations
and water testing
requirements per Texas
Commission on
Environmental Quality
guidance document(s)*
* Please visit www.tcep.state.tx.us for more information.
20
Conclusions:
• Rainwater is not subject to the same level of contamination as surface
water supplies, especially, when proper care is taken during the rain
harvesting process.
• The Texas Commission on Environmental Quality does not regulate the
use of rainwater for indoor uses in private homes that use rainwater as
their sole source of water supply (not connected to a public water system).
• For rainwater to be used indoors for non -potable purposes, total coliforms
should be less than 500 cfu/100 ml and fecal coliforms should be less than
100 cfu/100 ml; testing is recommended on an annual basis.
• For potable use, rainwater should undergo adequate filtration to maintain
turbidity below 1 NTU. A level not exceeding 0.3 NTU is required if the
rainwater is used in conjunction with a community or public water system.
In addition, proper disinfection is needed to maintain a level of zero
coliforms and no Giardia, Cryptosporidium, or viruses.
• Water testing is recommended on a quarterly basis for individual
residences, and monthly for community and public water systems. Public
facilities providing rainwater for drinking will be subject to the same health
protection goals and requirements as other public water systems.
• The Texas Commission on Environmental Quality will allow alternate
methods of filtration and disinfection for rainwater systems under their
innovative/alternate treatment methodologies.
• Water samples can be analyzed for microbiological and chemical
contaminants at many health department, water utility, and river authority
laboratories. Laboratories accredited by the Texas Commission on
Environmental Quality for this analysis can be found on their website.
21
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22
Chapter 4 - Treatment Methods for Indoor Use of Rainwater
A number of steps can be taken to help ensure the successful use of rainwater
for indoor purposes. First, any tree branches and vegetation that overhang roof
surfaces should be removed so that contamination caused by birds and rodents
on the branches is not washed down to the roof. Gutters may be screened or
leaf -guards installed to prevent larger objects from washing down from the roof.
The impact of any impurities, such as dust and bird or animal droppings from the
roof surface, can be minimized by using first -flush diverters that drain the first few
gallons of water. As a rule of thumb, first -flush diverters should be capable of
diverting at least 10 gallons per 1,000 square feet of roof area. A description of
various types of first flush diverters and roof washers (pre -filters) is provided in
Chapter 2 of the Texas Manual on Rainwater Harvesting (TWDB, 2005).
The manual can be accessed online at
http://www.twdb.state.tx.us/publications/reports/RainwaterHarvesting Manual 3rd
edition.pdf
or hard copies may be ordered from the TWDB, by calling (512) 463-7955.
The next step in the treatment process is filtering the water to remove fine
particulates. The level of filtration and disinfection required for rainwater depends
on the quality of the collected water and the purpose for which it will be used. In
addition to filtration, rainwater for indoor use should undergo disinfection to
remove any microorganisms.
Treatment Methods for Non -potable Indoor Use of Rainwater
Storage
After passing through the roof washer indicated above, rainwater for non -potable
indoor uses may be stored in any leak -proof tank or cistern. Tanks should be
kept tightly covered to inhibit mosquitoes and keep out other contaminants, and
protected from light to control the growth of algae, and to. A more complete
discussion of storage tanks is provided in the Texas Manual on Rainwater
Harvesting (TWDB, 2005).
Filtration
Cartridge filters may be placed on the discharge side of the pump, which
provides pressure to the plumbing system. To ensure adequate flow and
pressure of the water supply, the filters need to be sized to the intended use of
W
the water. A number of different filters can be used to provide the particulate
removal necessary to address adequately non -potable water uses. In general, a
nominal 5 micron (um) filter is sufficient for non -potable indoor uses. Filters of
different sizes and from numerous manufacturers are commercially available.
The Texas Rainwater Harvesting Evaluation Committee recommends the use of
filters certified by the National Sanitation Foundation (NSF).
Disinfection
Disinfecting non -potable rainwater for indoor use is desirable to control microbial
growth which could cause fouling and affect the operation of plumbng fixtures.
Disinfection can be accomplished by passing the water through ultraviolet light or
by treating it with chlorine. Chlorination may be accomplished simply by adding
bleach to storage tanks or cisterns on a regular basis. Readily available
household bleach (6 percent sodium hypochlorite) may be applied to the cistern
at the rate of 2 fluid ounces per 1,000 gallons of water to achieve disinfection.
Alternatively, in-line disinfection using bleach can be accomplished by using an
injection pump to dose the water and maintain a level of 0.2 parts per million of
chlorine residual.
Treatment Methods for Potable Use of Rainwater
Harvested rainwater that is intended for potable use requires a higher level of
treatment than that for non -potable uses. In addition, an extra measure of
diligence is necessary to maintain the safety of the harvested rainwater during
storage, filtration, and disinfection.
Storage
After the rainwater is pre -filtered through appropriate first -flush diverters and/or
roof washers, it should be stored in a leak -proof tank or cistern that has been
approved for potable use by the Food and Drug Administration, National
Sanitation Foundation, or the U.S. Department of Agriculture. The storage tank
must be kept tightly covered, properly vented, and protected from light to control
the growth of algae and keep out contaminants. Additional discussion of storage
tanks is available in the Texas Manual on Rainwater Harvesting (TWDB, 2005).
Filtration
Cartridge filters may be placed on the discharge side of the pump, which
provides pressure to the plumbing system. A number of different kinds of filters
can be used to provide the particulate removal necessary to adequately address
potable water uses. A filter that is capable of removing at least 99 percent of the
particles that are 3 microns or larger in diameter is recommended for potable
water that is free of protozoan pathogens, and particles that may be harboring
24
smaller microbes or that may interfere with the disinfection process. If necessary,
an activated charcoal filter may also be added to improve the taste of drinking
water. Filters of different sizes and types from several manufacturers are
commercially available, but those certified by the National Sanitation Foundation
are recommended.
Disinfection
Disinfecting potable harvested rainwater is necessary to inactivate potentially
pathogenic microorganisms that are not physically removed by filtration. Readily
available sodium hypochlorite bleach may be used for disinfection. In order to
ensure that disinfection is taking place and that there is enough chlorine in the
system, a chlorine residual of at least 0.2 mg/I must be maintained at all times in
the distribution system. Chlorine residuals can be easily measured using a test
kit. Because chlorine does not kill Giardia or Cryptosporidium, a cartridge or
membrane filter (that removes at least 99 percent of the particles which are 3
microns are larger in diameter) is preferred, followed by ultraviolet light for
disinfection.
Ultraviolet Disinfection
Ultraviolet disinfection has been used in the water and wastewater industry for
many years in Europe. However, regulatory recognition of ultraviolet disinfection
was accorded in the United States only recently by the Environmental Protection
Agency's adoption of the Long Term Phase 2 Enhanced Surface Water
Treatment Rule (LT2). This rule has established the benchmark for the use of
ultraviolet light for disinfecting drinking water.
Previously an ultraviolet dose capable of producing an energy of at least 40,000
uwsec/cm2 (40 mJ/cm2) was recognized, based on a National Sanitation
Foundation recommendation that was consistent with European standards for
inactivating bacteria, parasitic cysts, and most viruses. Because some viruses,
such as adenovirus, an agent in gastrointestinal illnesses in children, are more
resistant due to the virus' double-stranded DNA, the Environmental Protection
Agency is considering a higher ultraviolet dose of 186 mJ/cm2 to inactivate these
viruses also. Current or new rainwater harvesting ultraviolet systems will be able
to increase the ultraviolet dose by increasing the number of lamps and/or
exposure time within their system, or by pre -treating with chlorine. Increased
ultraviolet dosage, regular inspection, and certification for the new standard is
recommended for small rainwater harvesting systems that are used for potable
purposes, or for any larger public water system where ultraviolet is used as a
disinfectant in place of chlorine.
The recommended treatment methods for potable and non -potable indoor uses
of rainwater are shown in Table 2.
25
Table 2. Recommended Treatment Methods for Indoor Use of Rainwater
Treatment Methods for Non -Potable
Indoor Use of Rainwater
Treatment Methods for Potable Use
of Rainwater
Pre -filtration
Pre -filtration
First flush, roof washer, and/or
First flush, roof washer, and/or
other appropriate pre -filtration
other appropriate pre -filtration
method
method
Cartridge Filtration
Stora e
5 micron sediment filter
Storage of rainwater only in tanks or
cisterns approved for potable use
Disinfection
Cartridge Filtration
Chlorination with household bleach
3 micron sediment filter, followed by a
or
3 micron activated carbon filter
Ultraviolet light
Disinfection
A chlorine residual of at least 0.2 parts
per million maintained in the
distribution system at all times
Or
Ultraviolet light for disinfection with a
dosage of 186 mJ/cm2 for virus
inactivation
(Refer to the Texas Commission on
Environmental Quality Guidance
Documents for details)*
*Please visit www.tceg.state.tx.us for more information.
26
Conclusions:
• A number of precautionary steps can reduce contamination of rainwater
even before it is collected in tanks or cisterns.
• A first -flush roof washer or other appropriate pre -filtration is recommended
prior to storing rainwater in a tank or cistern.
• For non -potable indoor uses, a 5 micron filter may be used, followed by
chlorination with bleach at the rate of 2 ounces per 1,000 gallons of water.
• For potable indoor uses, only tanks/cisterns and cistern liners that are
approved for potable use by the Food and Drug Administration,
Environmental Protection Agency, or National Sanitation Foundation
should be used.
• For potable indoor uses, a 3 micron filter is recommended, followed by
ultraviolet disinfection to inactivate bacteria, parasitic cysts, and most
viruses.
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Chapter 5 - Using Rainwater Harvesting Systems in
Conjunction with Public Water Systems
House Bill 2430 required the Texas Rainwater Harvesting Evaluation Committee
to recommend ways such as dual plumbing systems, to use rainwater harvesting
systems in conjunction with existing municipal water systems. The terms
`municipal water systems' and 'public water systems' are used synonymously in
this report.
There are currently several examples in Texas where rainwater is being used in
combination with public water systems for landscape irrigation, such as the Lady
Bird Johnson Wildflower Research Center and the Wells Branch Municipal Utility
District Office in Austin. Other examples include: the Hays and Kerrville County
Extension offices in San Marcos and Kerrville, respectively; the New Braunfels
Municipal Building; the Van Horn Courthouse; the Edwards Aquifer Authority
Office in San Antonio; the Paint Rock High School in Paint Rock; and the Menard
Grade School in Menard, Texas.
Rainwater is also being used in conjunction with public water systems for non -
potable indoor uses. The J.J. Pickle Elementary School in Austin uses rainwater
collected from its rooftop to provide cooling water for the air-conditioning system.
The Austin Resource Center for the Homeless is using rainwater for toilet
flushing, and the Lower Colorado River Authority is currently constructing an
office building in Austin that will collect and use rainwater for toilet flushing and
irrigation.
Other communities around the country are also using rainwater systems along
with public water systems. For example, Portland, Oregon, the State of
Washington, Santa Fe, New Mexico, and Tucson, Arizona, have included various
requirements relating to rainwater use in their codes and guidelines.
Rainwater harvesting systems are being used in Europe, Asia, Australia, and in
the Caribbean. Germany has been a leader in promoting the widespread use of
rainwater for domestic use, focusing mainly on non -potable uses such as
irrigation, toilet flushing, and laundry use. France has recently enacted legislation
to encourage the use of rainwater through tax credits. In New South Wales,
Australia, the government is requiring a 40 percent reduction in water use, and
some studies have shown that rainwater harvesting systems can' reduce
municipal water demand there significantly (Coombes, 2004). The U.S. Virgin
Islands, the Bahamas, Bermuda, and other Caribbean islands, require cisterns to
be included with all new construction.
There are numerous other examples around the world where rainwater
harvesting is being promoted to conserve water and help reduce the demand on
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municipal water systems. Rainwater harvesting systems benefit both the public
water systems and the homeowners.
The Texas Rainwater Harvesting Evaluation Committee believes that this is a
great opportunity for Texas to take a lead in promoting rainwater harvesting
systems in conjunction with existing public water systems, not only for residential
purposes, but also for commercial and industrial applications. The hotel industry
for example, can save a significant amount of water and money if they use
rainwater for their laundry.
The Texas Rainwater Harvesting Evaluation Committee recommends that when
used in conjunction with public water systems, harvested rainwater be used for
outdoor (landscape) watering and indoor non -potable uses such as washing
machines and toilets.
Toilets and washing machines consume about 40 percent of the water that is
used inside the home (Vickers, 2001). If those two uses can be served with
rainwater, a significant saving will result to the homeowner. It will also help
utilities delay expansion of their water treatment facilities if rainwater can serve
as a supplementary source. A typical schematic recommended for rainwater
used in conjunction with a public water supply is shown below:
Municipal Supply
Rainwater Building
RPZ
Potable Uses
Cistern ( I RPZ
P CF DI W
Non -Potable
Uses
P=Pump; CF=Cartridge Filtration; DI = Disinfection; W=Washing Machine; T=Toilets;
RPZ = Reduced Pressure Zone Back Flow Preventer.
Figure 4. A schematic showing the conjunctive use of public water systems for
potable uses, and rainwater for non -potable uses (washing machines and toilets).
Public water systems serve as a backup source for the cistern, with an air gap to
prevent any cross -contamination. If at any time the cistern, pump, or other
equipment becomes nonfunctional, the public water system could also serve the
non -potable needs through a reduced pressure zone back-flow preventer valve.
A dual plumbing system used for rainwater harvesting in conjunction with a public
water system in Australia is shown in Figure 5. To meet Texas standards
however, such a system would be required to have a reduced pressure zone
back flow preventer at the meter, and an air gap for public water supply entry into
the storage tank.
Figure 5. An example of a dual plumbing system used in Australia.
Rainwater System Components Used in Conjunction with a Public Water
System
The system components being recommended in this report are consistent with
state rules and recommendations to ensure the public's health and safety.
The guidelines for roof washers, cisterns, and water treatment found in Chapters
3 and 4 of this report should be met for any system that is using rainwater
conjunctively with a public water supply. In addition, several system components
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must be addressed to protect both individual occupants and the public water
system from contamination, including proper cross -connection control, system
marking, and system maintenance.
Protection from Cross -Contamination
To keep rainwater from entering the public water system due to a drop in
pressure in the utility's distribution system, an appropriate backflow prevention
device or air gap should be used. This recommendation is based on the Texas
Commission on Environmental Quality's rules for public drinking water systems
that allow either an air gap or backflow prevention assembly, depending upon the
type of potential hazard (Title 20, Texas Administrative Code, Chapter
290.44(h)).
Where non -potable rainwater pipe and public water system pipe are installed in
the same trench, wall cavity, or other enclosed area, the pipes should be
separated in accordance with local codes.
If a pump is used for rainwater in conjunction with a public water system, it is
recommended that the pump and all other pump components be listed and
approved for use with potable water systems. The pump should be capable of
delivering a minimum residual pressure of 35 pounds per square inch, which is
required by the Texas Commission on Environmental Quality rules (30 TAC
Chapter 290.44(d)).
Piping and Labeling
If a rainwater harvesting system is used in conjunction with a public water system
at any facility, the Texas Rainwater Harvesting Evaluation Committee
recommends that the rainwater pipe be labeled for non -potable uses. The pipe
should be painted in black lettering "RAINWATER — DO NOT DRINK" on a bright
orange background. The lettering should be in bold and clearly visible. The label
should be painted at two -foot intervals throughout the length of the pipe. If
rainwater is mixed with other sources, such as air conditioning condensate or
reclaimed water, purple pipe should be used.
Every toilet, urinal, hose bib, irrigation outlet, or other fixture that uses rainwater
should be permanently identified as non -potable rainwater by the above labeling.
The pipe materials should meet the standards for domestic water. Fittings and
other system components should be listed for use in residential construction.
Both piping and fittings, as well as any other product used for the system, should
be installed as required by applicable federal and state codes and standards.
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Public Water System Issues
Public water system customers that also have rainwater harvesting systems must
install a reduced pressure zone backflow preventer at the service meter. The
public water system should also require the customer to meet all applicable
health and safety standards per building and plumbing codes and provide a
signed contract stating that all plumbing code requirements have been met. In
addition, rainwater harvesting systems that are used in conjunction with a public
water system should be recorded in the billing system. If the owner of a
rainwater harvesting system either stops using or fails to maintain the system
properly in accordance with public water system standards, the public water
system should require that the rainwater harvesting system be abandoned, and
this should be recorded in the public water system billing system.
The public water system operators should be knowledgeable about rainwater
systems. While there are currently no licensing and certifications for rainwater
system maintenance, it is recommended that the operators take any future
training that becomes available regarding rainwater harvesting.
Codes and Regulatory Issues
The Texas State Board of Plumbing Examiners governs plumbing regulations for
municipalities in Texas. Most communities follow one of two national plumbing
codes - either the Uniform Plumbing Code or the International Plumbing Code.
Rainwater harvesting is currently not addressed in either code.
Section 341.034 of the Texas Health and Safety Code regulates licensing and
registration of persons who perform duties relating to public water systems,
including backflow prevention and cross connection. The current training
conducted by the Texas State Board of Plumbing Examiners for licensed
plumbers and water utility operators does not include information regarding
rainwater systems. Plumbers must complete six hours of continuing education
credits every year to maintain their license, and rainwater harvesting systems
should be included in their continuing education courses. Also, a rainwater
harvesting component should be included in the Texas State Board of Plumbing
Examiner's current "water supply protection endorsement".
It is recommended that the state develop a certification program for consultants
and contractors to properly design, install, and maintain rainwater harvesting
systems. In addition to rainwater harvesting system design, this program needs
to include some basic knowledge of plumbing and public water system
requirements.
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Finally, it is recommended that training on rainwater harvesting systems be
added to the current training for city permitting staff, building inspectors,
plumbers, and water utility operators.
Conclusions:
• Rainwater harvesting systems are already being used in conjunction with
municipal or public water systems in other parts of the country, in Europe,
Asia, and Australia.
• The Texas Rainwater Harvesting Evaluation Committee recommends that
when used in conjunction with public water systems, rainwater be used
for landscape watering and non -potable indoor uses only, such as
washing clothes and toilet flushing.
• Toilets and washing machines consume about 40 percent of indoor water
use, so if rainwater could be used for those purposes, it would constitute a
significant saving to homeowners.
• Rainwater harvesting systems can help cities conserve water and possibly
assist in delaying the expansion of their water treatment systems.
• Rainwater harvesting systems can help reduce peak discharge to storm
sewers, especially during high-intensity storms.
• Rainwater harvesting systems can save the hotel industry a significant
amount of money, if they use rainwater for their daily laundry
requirements.
• Rainwater harvesting systems may be used in conjunction with public
water supplies, if a reduced pressure zone back flow preventer is installed
or an air gap maintained to prevent rainwater from coming into contact
with public water systems.
• If a facility uses rainwater in combination with water from a public water
system, the pipes and fixtures for conveying the rainwater should be
labeled in a bright orange color, as explained in this report.
• If rainwater harvesting systems are used in conjunction with public water
systems, the installers of such systems need to be certified or licensed.
• Rainwater harvesting system recommendations should be incorporated in
all city building and plumbing codes.
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Chapter 6 - Recommendations for Promoting Rainwater
Harvesting in Texas
House Bill 2430 required the Texas Rainwater Harvesting Evaluation Committee
to recommend ways in which the state can further promote rainwater harvesting.
Members of this committee evaluated various aspects of rainwater harvesting
systems and public water systems in developing these recommendations.
In addition, Texas members of the American Rainwater Catchment Systems
Association were contacted to provide their suggestions as well. All suggestions
and recommendations were evaluated and the following 10 key
recommendations were selected (also included in the Executive Summary):
Key recommendations:
Directing new state facilities with 10,000 square feet or greater in roof
area (and smaller facilities, when feasible), to incorporate rainwater
harvesting systems into their design and construction. Harvested
rainwater at these locations may be used for restroom facilities
and/or landscape watering.
2. Developing incentive programs to encourage the incorporation of
rainwater harvesting systems into the design and construction of new
residential, commercial, and industrial facilities in the state.
3. Considering a biennial appropriation of $500,000 to the TWDB to
help provide matching grants for rainwater harvesting demonstration
projects across the state.
4. Directing the Texas Commission on Environmental Quality and other
state agencies to continue to exempt homes that use rainwater
harvesting as their sole source of water supply from water quality
regulations that may be required of public water systems. Guidelines
are provided in this report to assist homeowners in improving and
maintaining the quality of rainwater for indoor uses.
5. Directing the Texas Commission on Environmental Quality and other
state agencies to require those facilities that use both public water
supplies and harvested rainwater for indoor purposes to have
appropriate cross -connection safeguards, and to use the rainwater
only for non -potable indoor purposes.
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6. Appropriating $250,000 to the Texas Department of State Health
Services to conduct a public health epidemiologic field and laboratory
study to assess the pre- and post-treatment water quality from
different types of rainwater harvesting systems in Texas, and to
submit a report of findings to the next session of the legislature.
7. Directing Texas cities to enact ordinances requiring their permitting
staff and building inspectors to become more knowledgeable about
rainwater harvesting systems, and permit such systems in homes
and other buildings, when properly designed.
8. Directing a cooperative effort by the Texas Commission on
Environmental Quality and the Texas State Board of Plumbing
Examiners to develop a certification program on rainwater harvesting
and provide associated training in their continuing education
programs.
9. Directing Texas Cooperative Extension to expand their training and
information dissemination programs to include rainwater harvesting
for indoor uses.
10. Encouraging Texas institutions of higher education and technical
colleges to develop curricula and provide instruction on rainwater
harvesting technology.
In addition to the above key recommendations, several other suggestions were
submitted to and considered by the Texas Rainwater Harvesting Evaluation
Committee; they are included as an appendix to this report.
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References:
American Rainwater Catchment Systems Association, 2005, Draft ARCSA
guidelines for rainwater harvesting systems.
AWWA (American Water Works Association), 2006, Field guide to SDWA
regulations.
Australia Capital Territory Government, 2004, Rainwater tanks—guidelines for
residential properties in Canberra.
Coombes, Peter J., Spinks, A., Evans, C., and Dunstan, H., 2004, Performance
of rainwater tanks in Carrington, NSW during a drought, WSUD, Australia.
Konig, K. W., The rainwater technology handbook: Germany, Wilo-Brain.
Krishna, Hari J., 2003, An overview of rainwater harvesting systems and
guidelines in the United States, Paper presented at the First American Rainwater
Harvesting Conference, Austin, TX.
Krishna, Hari J., 2005, The success of rainwater harvesting in Texas – a model
for other states, Paper presented at the North American Rainwater Harvesting
Conference, Seattle, WA.
Lye, Dennis, 2005, Rainwater catchment systems in Ohio and Kentucky: future
directions, Paper presented at the North American Rainwater Harvesting
Conference, Seattle, WA.
Lye, Dennis, 2003, Application of USEPA's drinking water regulations toward
rainwater catchment systems, Paper presented at the First American Rainwater
Harvesting Conference, Austin,TX.
Macomber, Patricia S., 2001, Guidelines on rainwater catchment systems for
Hawaii: University of Hawaii at Manoa.
City of Portland, Oregon, Office of Planning and Development Review Code
Guide, Rainwater Harvesting - ICC - Res/34/#1 & UPC/6/#2.
TRCC (Texas Residential Construction Commission), 2005, Report of the rain
harvesting and water recycling task force.
TWDB (Texas Water Development Board), 2005, The Texas manual on
rainwater harvesting. Third Edition.
Vickers, A., 2001, Handbook of water use and conservation: Water Plow Press
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Appendix
Other Suggestions for Promoting Rainwater Harvesting
The following suggestions were submitted to and considered by the Texas
Rainwater Harvesting Evaluation Committee:
1. Design and installation specifications for rainwater harvesting systems
should be developed by state agencies, and included in the Texas
Building Code and Energy Performance Standards.
2. The Texas Department of Transportation and the Texas Parks
and Wildlife Department should consider rainwater harvesting for toilet
flushing and/or landscape use at highway rest areas and state parks.
3. Under Senate Bill 2, passed in 2001, all local taxing entities in Texas
should consider providing blanket exemption on the cost of rainwater
harvesting equipment from being added to the value of any commercial,
industrial, or residential property for property tax assessment.
4. All cities and local taxing entities should consider amending their land
development regulations to exempt roof areas used for rainwater harvesting
from being considered as impervious cover.
5. Cities, local communities, and Texas Cooperative Extension should provide
more publicity on the sales tax exemption for rainwater harvesting equipment
and supplies found in Tax Code Section 151.355.
6. Cities should organize local meetings and workshops to bring together their
permitting staff, architects, engineers, builders, and mortgage lenders so that
a communitywide effort can be made to promote rainwater harvesting for
commercial, industrial and residential applications.
7. Regional water planners should give greater consideration to using
rainwater harvesting as a source of alternate water supply.
8. Local economic development corporations in Texas should consider
including rainwater harvesting projects for funding eligibility.
9. Cities should recognize and provide awards to local facilities that use
the best rainwater harvesting techniques, in order to encourage others
to practice rainwater harvesting.
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Acknowledgements
The Texas Rainwater Harvesting Evaluation Committee wishes to acknowledge
the assistance of the following Texas Water Development Board staff during
the preparation of this report: Kevin Kluge, Yun-Jeong Cho, Mark Hayes,
Miguel Pavon, and Felicia Retiz.
The committee greatly appreciates the technical material from Dr. Dennis Lye
(U.S. Environmental Protection Agency, Cincinnati, OH), Dr. Peter Coombes
(Australia), and Klaus Konig (Germany). The committee also appreciates the
cooperation of Pioneer Water Tanks - a BlueScope Water Company in allowing
us the use of their schematic to illustrate a dual plumbing system in Australia.
A draft of this report was reviewed by Bill Mullican, Jorge Arroyo, John Sutton,
Dr. Sanjeev Kalaswad and Ruben Ochoa at the Texas Water Development
Board, and by Patricia Macomber at the University of Hawaii, all of whom
provided many useful comments.
The committee appreciates very much the information provided by the resource
persons listed on the next page of this report, and the comments provided by Dr.
Casey Barton, Billy Kniffen (Texas cooperative Extension), Dana Nichols (San
Antonio Water System), Lisa Hill (Texas State Board of Plumbing Examiners),
Dan McNabb and Danny Lytle (both from City of Austin), and Joseph Wheeler
(Rainfilters of Texas, LLC).
During the public comment period, 30 comments were received and reviewed by
the committee. We wish to thank all those who submitted their comments to us
on the draft report.
Texas Rainwater Harvesting Evaluation Committee
Austin, Texas
November 2006
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Texas Rainwater Harvesting Evaluation Committee
Members, Alternate Members, and Resource Persons:
Members: Dr. Hari J. Krishna, P.E., P.H. (Chair)
Texas Water Development Board
Anthony Bennett, R.S. and Buck Henderson
Texas Commission on Environmental Quality
Ken Ofunrein, R.S.
Texas Department of State Health Services
Nora Mullarkey, M.P.H.
Texas Section of the American Water Works Association
Conservation and Reuse Division
Alternate Stacy Pandey (Texas Water Development Board)
Members: Mike Lannen (Texas Commission on Environmental Quality)
Marcia Becker, M.P.H. (Texas Department of State Health Services)
Chris Brown (Texas Section of the American Water Works
Association, Conservation and Reuse Division)
Resource John Kight, P.E., Boerne, Texas
Persons: Allan Standen, P.G., Daniel Stephens & Associates, Austin
Bill Hoffman, P.E., City of Austin
Rusty Osborne, University of Texas at Austin
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