Ohio Department of Health
Bureau of Environmental Health
Plans for Developing a Rainwater
Cistern or Hauled Water Supply
“To improve and protect the health of all Ohioans”
February 29, 2012
246 North High Street
Columbus, Ohio 43215 614/466-1390
www.odh.state.oh.us
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Table of Contents
Sizing your cistern or Hauled Water Storage Tank as a Private System 1
Water Use Estimates may be Based on the Following Averages 2
Annual Rainfall Yield in Gallons for Various Roof Sizes 2
Average Annual Precipitation 3
Installing the Cistern or Hauled Water Storage Tank 4
Permits 4
Locating the cistern 4
Roofs, Gutters, Downspouts, and Roof Washers 4
Maintenance of Gutters, Downspouts, Debris Traps, Roof Waters and Cistern Filters 8
Tanks 9
Re ll Pipe 10
Water Intake into House 11
Disinfection and Treatment 12
Procedures for Cleaning Cisterns and Hauled Water Storage Tanks 13
Illustrations
Example of Gutter Guard 5
Example of Automatic Diverters 5
Examples of Filtering Roof Washers 6
Example of Home Built Roof Washers 6
Example Drawing of An Optional Cistern Sand Filter 8
Example Drawings of a Concrete Cistern 9
Example of Chlorine or Iodine System for Continuous Disinfection 13
Example of an Ultraviolet Light System for Continuous Disinfection 13
Plans for Developing a Rainwater Cistern of Hauled Water Supply
1
Plans for Developing a Rainwater Cistern of Hauled Water Supply
The construction of rainwater cisterns and hauled water storage tanks used as
private water supplies in Ohio is covered in Ohio Administrative Code (OAC) 3701-28-12. Cistern
and hauled water tank con gurations may vary by contractor and do not necessarily need to
correspond with all of the examples provided in this document as long as it is constructed in
compliance with the Rules. Contact your local health department for the necessary permits
and for additional information.
A cistern is a type of water system that collects rainwater o of a roof and channels it through
gutters to a collection tank for storage until used by the household. Cisterns may also be referred
to as a rainwater catchment or rainwater harvesting systems. A hauled water storage system is
not designed to collect water o a roof but is simply a water tank that is re lled exclusively by
truck deliveries from OEPA regulated public water supplies. Water haulers must comply with
OAC Rule 3701-28-16 before they can deliver water to private drinking water cisterns or hauled
water storage tanks. Local health departments inspect these water hauling trucks annually for
compliance with OAC Rule 3701-28-16.
Cisterns and hauled water storage tanks may be used where ground water is not available or
is impractical to treat for home use. Cisterns are required to have continuous disinfection in
accordance with OAC Rule 3701-28-15 in order to make the water sanitary for potable uses.
Hauled water storage tanks are not required to have any additional treatment.
Sizing Your Cistern or Hauled Water Storage Tank
as a Private Water System
In Ohio the minimum required size of a cistern is 2500 gallons and the
minimum required size for a hauled water storage tank is 1000 gallons
when used as private water systems. However, the overall size should be based on the expected
water needs of the household. The ideal storage capacity of the cistern can be calculated based on
the longest drought period within the last 50 years. A safety factor of 25 % is then added to that.
Ohio experiences about 37 inches of rainfall per year. Monthly average rainfall can vary greatly.
It may rain as much as seven inches in an above normal wet month and as little as zero in other
months. The Hydrologic Atlas for Ohio (1991), Water Inventory Report 28, provides additional
information on average annual rainfall across Ohio for a 50 year period (1931-86). A copy of this
document can be obtained from the Ohio Department of Natural Resources, Division of Water or
at
http://www.dnr.state.oh.us/water/pubs/fs_div/fctsht11/tabid/4094/Default.aspx
Seven inches of rainfall on a 1500 square foot roof will yield about 6300 gallons. Most of this
water would be wasted if the storage capacity of the cistern were the minimum 2500 gallons.
Therefore it is recommended that a cistern to be used as the primary water source for a year
round residence should have at least a 6000 gallon to 10,000 gallon capacity using one or more
tanks. It is very likely that a cistern water supply will have to be supplemented from a hauled
water delivery company.
The overall size of
a Cistern should be
based on expected
water needs of the
household
2
Plans for Developing a Rainwater Cistern of Hauled Water Supply
The cistern may also be sized based on the following roof areas:
Roof Area in Square Feet Gallons Capacity of Cistern
Less than 1000 2500 to 5000
1000-1500 7500
1500-2000 10,000
2000 or more 12,500+
Water use estimates may be based on the following averages:
• Typical home use 60 gallons per person per day. Cistern users are generally more
conservative with water usage.
• Estimated annual use family of four would be about 87,600 gallons.
• Garden or lawn watering to apply one inch for 1000 square feet – 625 gallons per day.
To estimate the potential yield, calculate the rainfall (monthly or yearly) in inches multiply 0.6
times the square footage of the roof catchment area.
Annual Rainfall Yield in Gallons for Various Roof Sizes
Roof Area
Square Feet
1000
Rainfall
In
Inches
24
28
32 36 40 44
48 52
13483 15730
17978 20225 22472 24719
26966 29214
1100 14832 17303
19775 22247 24719 27191
29663 32135
1200 16180 18876
21573 24270 26966 29663
32360 35056
1300 17528 20450
23371 26292 29214 32135
35056 37978
1400 18876 22023
25169 28315 31461 34607
37753 40899
1500 20225 23596
26966 30337 33708 37079
40450 43820
1600 21573 25169
28764 32360 35955 39551
43146 46742
1700 22921 26742
30562 34382 38202 42023
45843 49663
1800 24270 28315
32360 36405 40450 44495
48540 52584
1900 25618 29888
34157 38427 42697 46966
51236 55506
2000 26966 31461
35955 40450 44944 49438
53933 58427
2100 28315 33034
37753 42472 47191 51910
56629 61349
2200 29663 34607
39551 44495 49438 54382
59326 64270
2300 31011 36180
41348 46517 51686 56854
62023 67191
2400 32360 37753
43146 48540 53933 59326
64719 70113
2500 33708 39326
44944 50562 56180 61798
67416 73034
Ohio average yields in bold (Table by Woods and Choudhury 1991)
3
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Average Annual Precipitation
(Recorded from 1931-1980)
Amount in Inches
29-31
31-33
33-35
35-37
37-39
39-41
41-43
43-45
4
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Installing the Cistern or Hauled Water Storage Tank
Permits
Ohio Administrative Code 3701-28-12 describes the construction requirements of cisterns
and hauled water storage tanks used as potable water supplies. A permit is required from the
local health department prior to beginning construction or doing an alteration on a cistern
or hauled water storage tank. When an alteration is done on an existing cistern, there is a
requirement to up-grade the treatment system to comply with the current rules. Any work done
on a drinking water cistern or hauled water storage tank must be done by a contractor registered as
a Private Water Systems Contractor with the Ohio Department of Health (this is not the same as a
licensed plumber). This includes the excavation, the tank placement, connection to the house, and
installation of the disinfection system. The local health department will have a listing of registered
contractors in the area.
Locating the Cistern or Hauled Water Storage Tank
Cisterns and hauled water storage tanks should be located away from sources of
contamination based on the isolation distance requirements set forth in Ohio Administrative
Code (OAC) 3710-28-07. A cistern or hauled water storage tank may share a common
wall with a building as long as that is also acceptable local building or
construction codes. A new cistern or hauled water storage tank may not be
located within a foundation of a building. Also consider the location of
trees in proximity to the roof in order to reduce debris. A cistern or hauled
water storage tank must be at least 50 feet from most septic systems (including
the sewage tank) and 100 feet away from a leaching pit and privy type septic
systems.
Roofs, Gutters, Downspouts, and Roof Washers For Rainwater Cisterns
Ohio does not certify or approve roof or gutter materials for the collection of rainwater for
drinking. The best roof materials for drinking water catchments are clay and slate tiles, metal,
and cementitious (non-asbestos). Other roo ng materials used in many parts of the world
thought to be suitable for rainwater collection are asphalt shingles, corrugated galvanized
steel, aluminum alloy sheeting, corrugated cement ber sheeting, corrugated plastic, and
bituminous sheeting. Lead materials should not be used anywhere on the roof where there is
contact with water leading to the cistern. There should be an additional particle lter device
installed with the treatment system if asphalt shingles are used.
The local industry and land use practices will also have an in uence on the water quality of
rainwater. Past studies of the roof and gutter catchment surfaces in urban and industrial areas
had been characterized by higher levels of lead from motor vehicles. Lead levels should be
currently reduced due to the elimination of lead from gasoline. Rainwater from agricultural
Cisterns should
be located away
from sources of
contamination
5
Plans for Developing a Rainwater Cistern of Hauled Water Supply
areas has also shown increased levels of nitrates and pesticides due to farm eld applications.
The highest quality rainwater will tend to come from rural areas with low agricultural activity.
The use of a granular activated carbon (GAC) is recommended to remove possible pesticide
residuals in areas where agricultural use deposition is possible.
Use gutter guards to exclude leaves and twigs. A roof washer / lter shall be provided for each
1500 square feet of roof area. A rainwater diverter should also be installed to clean the roof with
the initial ush of rain. These diverters can be designed to have a manual lever switch inside or
outside the house or set up to work automatically (see drawings).
Roof
Slide under shingles
1/4” to 1/2” openings
Clip inside gutter
Examples of Automatic Diverters
Example A Manufactured Example B Manufactured
Example C Home Built
Note:
Problems will occur
with these devices if not
properly maintained on
a routine basis.
Rainwater Rainwater
Rainwater
Gutter Gutter
Gutter
Initial ush
Initial ush
Initial ush
Float closes
valve when
pipe is full
Ball closes
valve when
ball is full
diverting
water to
cistern
Float closes
valve when
pipe is full
diverting
the water to
cistern
4 to 8 “
storage pipe
4 to 8 “
storage pipe
Drip outlet
Drain and clean-out
Debris trap/
Roof washer
Debris trap/
Roof washer
Debris trap/
Roof washer
To cistern
To cistern
To cistern
Example of Gutter Guard
Not to scale
To drain
To cistern
To waste
Clip inside gutter
Simple Manual Diverter
6
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Examples of Filtering Roof Washers
Example A
Manufactured
Inlet from gutters
(two options)
Inner leaf basket
Over ow/
clean-out
Leaf catcher lid
Standard replaceable
lter element
Outlet to cistern
Ba e table
Quiet Chamber
Example B
Manufactured Double Roof
Washer for roof area greater than
1500 square feet
Over ow drain
Inner leaf basket
Inlet from gutters
(two options)
Quiet Chamber
Outlet to cistern
Over ow/
clean-out
Standard replaceable
lter element
Leaf catcher lid
Cross section view
7
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Examples of Home Built Roof Washers
Example A
Example B
Example C
Wire screen with 1/4” holes
1/4” weep hole
From roof
Wire screen with 1/4” holes
From roof
The barrel or
concrete tank
12” to 18” high min.
15” diameter
Sealing medium
Removable debris trap
Weep hole to
drain after rain
(1/4” diameter)
Air gap
To cistern
Gravel bedding
for stability
4” diameter
Concrete base (4” thick)
Ground level
To cistern
Concrete base
Removable debris trap
Tie barrel or concrete tank
Top View
4” diameter
Wire screen with 1/4” holes
1/4” weep hole
From roof
Wire screen with 1/4” holes
From roof
Barrel min.
15” diameter
Removable debris trap
Weep
hole to
drain after
rain (1/4”
diameter)
To cistern
Gravel bedding
for stability
Not to scale
Concrete base (4” thick)
Ground level
To cistern
Concrete base
Removable debris trap
Top View
Hole 4” diameter
12” to 18” high
Air gap
Approx. 6”
Wire screen with 1/4” holes
1/4” weep hole
From roof
Wire screen with 1/4” holes
From roof
Removable debris trap
Weep
hole to
drain after
rain (1/4”
diameter)
To cistern
Gravel bedding
for stability
Not to scale
Concrete base (4” thick)
Ground level
To cistern
Concrete base
Removable debris trap
The barrel or concrete tank
Top View
Hole 4” diameter
Air gap
Approx. 6”
Tie barrel or
concrete tank
12” to 18” high min.
15” diameter
Sealing medium
A roof washer/ lter
shall be provided for
each 1500 square feet
of roof area.
Note: Problems will occur with these
devices if not properly maintained on a
routine basis
4” dia. hole
4” dia. hole
The barrel or concrete tank
8
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Example of Drawing of an Optional Cistern Sand Filter
From roof
To waste
Ground level
Debris trap (removable metal tray with 1/4” holes)
Suggested media depth placement
30” acceptable lter sand
3” ne gravel (1/4”)
6” coarse gravel (3/4’)
To cistern
4” diameter
Gravel bedding for stability
Provide roughly 16 square feet of surface
area in each sand lter
Retention screen or grate
(to prevent media from entering pipe)
Note: Problems will occur with this device if not properly maintained on a routine basis.
Removable cover
(covered with metal sheeting)
Screened over ow
Maintenance of Gutters, Downspouts, Debris Traps,
Roof Washers and Cistern Filters
It is critical to routinely maintain gutters, downspouts, debris lters, roof washers, and cistern
sand and gravel lters. Weep-hole drains and over ow drains need to be kept clear to allow
free drainage. Failure to maintain the cistern roof washers, diverters and debris traps will allow
them to plug, over ow and cause rainwater to be wasted. When sand and gravel cistern lters
are used, the lter media must be cleaned to prevent plugging by partially removing the top
layer of lter media. The best time to do this is when the water ow through the lter has
become very slow. Replace the top of the lter bed with the same depth and type of media.
Flapper valve
9
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Tanks
Cisterns and hauled water storage tanks are placed below ground to minimize the chances
of the water supply freezing in the winter. The bottom of the excavation shall be continuous,
smooth, and free of rocks. The bottom of the excavation should have at least four inches of
sand or a similar granular ll material. The tank must be set level in the excavation and at an
adequate depth to prevent frost heave. The back ll must be free of large rocks and debris and
be graded so that water drains away from the tank.
Example Drawing of Concrete Cistern
From roof washer
or ltering device
min. 4” dia.
To pump
Floating intake
Manhole with
secure cover
Screened vent
Screened over ow
min. 4” dia.
Fill pipe with
secure cap
Min. 24”
Screened, inverted vent
pipe (not needed if
already vented to open
air thru inlets/outlets)
Optional string
for easy intake
cleaning
Min. 8” above
ground level
Secure cover
Min. 8” above
ground level
Min. 2” lip projecting
downward
Secure, watertight cap
Screened over ow
(provide only when
gravity outlet to
atmosphere is possible)
Floating intake min. 4”
below surface
Min. 4” dia.
Force breakers to dissipate in uent stream
To pump
(protected from
freezing)
From roof washer
or ltering device
min. 4” diameter
Force breaker
Water level
Top View
Min. 24”
Side View
Cistern: Watertight, Durable
Not to Scale
10
Plans for Developing a Rainwater Cistern of Hauled Water Supply
The interior of the tanks used as cistern and for hauled water storage should be made of a
smooth and watertight material. These materials can be plastic, berglass, or concrete. Plastic
and berglass material must meet National Sanitation Foundation (NSF) Standard 61 and
comply with FDA 21CFR 177.1520. Listings of NSF certi ed products can be found at
www.nsf.org. Concrete used for cistern and hauled water storage tank construction must
meet ASTM C-913 which means it has a material strength rating of at least 4000 psi, which is
the concrete industry equivalent standard used for water tightness. However, concrete by its
nature, still has some porosity. The interior of a tank may be sealed with liners or other sealing
materials that meet NSF Standard 61. These products can also be checked at
www.nsf.org.
Many cisterns are cast in two or more sections. When these sections are joined, the joining
and sealing materials must be non-toxic and meet NSF standard 61. Cast openings in walls or
top in a manner to insure a watertight connection. Manhole openings must be a minimum
of 24 inches in diameter to provide easy access for cleaning. The manhole opening should
be 8 to 12 inches from the ground. The manhole cover shall have watertight edges that
project downward at least two inches. The cover must be secured to minimize the danger
of contamination, accidents, and unwarranted entry. The cover can be secured by bolting or
having su cient weight (65 lbs.) that children cannot lift the cover.
A cistern tank must be installed with an over ow to drain excess water to the outside when
rainfall exceeds the capacity of the cistern. A hauled water storage tank may or may not have
an over ow installed based on the water hauler having the ability to control the lling process.
All over ows and vents must have a y screen animal guard of 43 thousands of an inch
installed to exclude small animals and insects.
Refi ll Pipe
There is a strong likelihood that water will have to be
hauled in to a cistern to supplement the household
supply during drier times. The ll pipe should be of
su cient size to dissipate the in-coming water and
minimize turbulence. This can be done by using a
4 inch PVC pipe that extends close to the bottom
of the cistern with force breakers (cast or movable
blocks) around and below the re ll pipe. These force
breakers help to dissipate the incoming water to
reduce stirring up sediment deposited on the oor of
the cistern or hauled water tank. A PVC cap should be
placed on the pipe when not being used for lling.
(Also see drawing on page 9.)
Min. 8” above
ground level
Screened over ow
(provide only when
gravity outlet to
atmosphere is possible)
Min. 4” dia.
Force breakers to dissipate in uent stream
Side View
Top View
Secure, watertight cap
11
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Precast threads
Pump
1” line
Water to house
Electric to house
Well Cap
5” PVC
3”
5”
Example of Alternative Intake
Floating intake
min. 4” below
surface
Force breakers to dissipate in uent stream
To pump
(protected from
freezing)
Water level
2. A submersible pump may be used as the water
intake. The pump should be placed so the pump
intake is at least 4 inches from the bottom of the
tank.
3. Alternative intake designs may be used as long as
water is not taken from any less than four inches
from the water surface and 4 inches from the
bottom.
Water Intake into House
The water intake to the house must be designed so that water is not pumped from the bottom
of the tank where debris can accumulate or skimmed from the surface where oating debris
can be present. This can be accomplished in several ways. (Also see example drawings of
cistern cutaway side view on page 9.)
1. The intake could be attached to a oating lter
device that maintains the opening to the intake
below the water surface. A jet pump would be
located in the house to pump the water to the
pressure tank.
4”
Side View
12
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Disinfection and Treatment
Rainwater cisterns are required to have continuous disinfection and cyst reduction.
Hauled water storage tanks are not required to have continuous disinfection
installed. However, any water that is delivered to a hauled water storage tank must
have a chlorine residual of 0.2 ppm at the time of delivery. The disinfection system
must be installed in accordance with OAC Rule 3701-28-15. Current acceptable
methods for continuous disinfection are chlorination, iodination, ozonation, and
ultraviolet (UV) light systems that meet NSF Standard 55 Class “A”. An absolute 5
micron lter is required to be installed when UV is used as the means of continuous
disinfection. A one to two micron cyst reduction lter that meets NSF Standard 53
is required to be installed with chlorination, iodination, and ozone systems and is
recommended for UV systems. These lters are designed to remove disease causing
protozoa such as cryptosporidium and giardia. The cyst lters need to be installed in
parallel in order to maintain a ow rate capacity of at least 10 gallons per minute.
Labels must be placed on each lter housing and treatment device, indicating the
proper replacement lter(s) and pore size indicated as absolute microns.
For treatment systems using chorine for disinfection a minimum 0.4 parts per
millions chemical residual must be present in the water after 8 minutes of chlorine
/ water contact in the retention (contact) tank. When iodine is used for disinfection,
the chemical residual should be between 0.5 and 1.0 parts per million after 20
minutes of contact in the retention tank. The retention (contact) tank shall have a
capacity of at least 120 gallons per household and be constructed with ba es or
lled with pea gravel that reduces short circuiting through the retention tank in
order to increase the retention time. The private water system contractor should
provide the home owner with a chemical test kit to periodically check the chlorine
residual leaving the system. The solution reservoir must always have chlorine
or iodine solution in it or the household water will not be getting disinfected.
It is recommended that a oat switch be installed in the solution tank attached
to a solenoid that will shut o the water when the solution tank has gone dry.
If UV is the disinfection of choice then an automatic shut o solenoid is highly
recommended for instances when the UV system is not functioning properly.
(See Ultraviolet Light for Continuous Disinfection fact sheet for more information).
13
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Example of a Chlorine or Iodine System for Continuous Disinfection
Chemical feed
pump runs when
well pump runs
Disinfectant
chemical
solution
tank
Standard pressure tank
From water source Pressure switch
120 gallon ba ed
chlorine retention
tank
Cyst
reduction
lters
To house
SHOULD NEVER
BE EMPTY!
Procedures for Cleaning Cisterns and
Hauled Water Storage Tanks*
Cisterns and hauled water storage tanks should be thoroughly cleaned periodically. How often
this is done is going to be dependent on the area in which you live. Because cisterns collect
rainwater o of the roof they are subject to varying amounts of potential contamination. In
areas where there are large trees overhanging the roof area, or in areas where there is a lot of
industrial activity, cistern cleaning should be performed more often. Cisterns in these types of
areas should be cleaned every three to ve years, but they may be cleaned more often if there
is a desire or a need to do so. Hauled water storage tank systems that use exclusively hauled
water will not require cleaning nearly as often as cisterns if care is taken when re- lling occurs.
Example of an Ultraviolet Light System for Continuous Disinfection
1. Pump
2. Pressure tank
3. Water softener
4. Pre lters
All precede the 5 micron lter
and ultraviolet light unit
Incoming
water
To house
UV monitor
and alarm
Ultraviolet solenoid shut-o
5 micron
or cyst
reduction
lters
must be
installed
in parallel
Not to
scale
14
Plans for Developing a Rainwater Cistern of Hauled Water Supply
Ohio Administrative Code 3701-28-12 (N) describes the startup, operation and disinfection of
cisterns and hauled water storage tanks.
* Entering an enclosed space such as a cistern or hauled water storage tank for cleaning can
be a dangerous procedure without adequate ventilation. We recommend that a quali ed
registered private water systems contractor carry out these procedures.
Steps:
1. Drain all of the old water from the tank.
2. Provide adequate ventilation by use of a fan or other mechanism.
3. Enter the inside of the tank. Make sure someone is around to provide assistance if required.
4. Physically remove all debris from the bottom and sides of tank.
5. With a sti brush or power washer, scrub the walls and oor with an unscented
chlorine water solution of su cient strength to remove any bacterial slime and mineral
encrustation.
6. Leave the inside of the tank and then rinse the walls with a strong chlorine water solution
of 1000 parts per million. This can be obtained by mixing two gallon of 5.25% unscented
chlorine bleach per each one hundred gallons of water. Leave a foot or more of water
standing in the bottom of tank. You will need enough water to re-circulate the chlorine
solution through the distribution system.
7. Circulate the chlorine solution throughout the distribution system and let stand for at least
eight hours.
8. Evacuate the rinse water.
9. Clean or replace the oating intake lter. Roof washer lters should be inspected and
cleaned twice per year.
10. Re ll the tank with chlorinated water hauled in from a public water supply. Water hauled
from a public water system must have a chlorine residual of 0.2 ppm at the time of delivery.
11. If continuous disinfection is by chemical means then re-calibrate the disinfection system
and check the disinfectant residual. Check the chemical residual at the sampling port just
after the retention (contact tank). Chorine shall be at least 0.4 ppm, iodine 0.5 ppm, and
ozone 0.1 ppm. Homeowners are required to have a chemical test kit for monitoring the
type of system in use.
Rev. 02/12
Ohio Department of Health
Bureau of Environmental Health
246 North High Street
Columbus, Ohio 43215 614/466-1390
www.odh.state.oh.us
