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Rain Barrels & Cisterns - Watershed Benefits
Rain barrels and
cisterns are low-cost water conservation devices that can be used to
reduce runoff volume and, for smaller storm events, delay and reduce the
peak runoff flow rates. By storing and diverting runoff from impervious
areas such as roofs, these devices reduce the undesirable impacts of
runoff that would otherwise flow swiftly into receiving waters and
contribute to flooding and erosion problems.
Typical rain barrel
set-up
for a residential property.
(Source:
District of Columbia
Water & Sewer Authority)
1500 gallon cistern
fed from two gable downspouts.
(Source:
Experiments in
Sustainable
Urban Living)
Although most
commonly used as a secondary source of water for gardening in
residential areas, larger sized cisterns can be adapted for use to
supplement potable water systems. Many municipalities are promoting the
use of cisterns for potable water use as well as for commercial and
industrial applications. Both rain barrels and cisterns can provide a
source of chemically untreated 'soft water' for gardens and compost,
free of most sediment and dissolved salts. Because residential
irrigation can account for up to 40% of domestic water consumption,
water conservation measures such as rain barrels can be used to reduce
the demand on the municipal water system, especially during the hot
summer months.1
The following table exhibits some of the site considerations of rain barrels
and cisterns.
Site Considerations
of Rain Barrels and Cisterns
|
|
Space Needed |
Soils |
Slopes |
Depth To Water Table |
Depth To Bedrock |
Proximity To Foundations |
Max. Depth |
Distance To Septic Tanks |
Maintenance |
|
Rain Barrel
|
Not a Factor
|
Not a Factor |
Usually not a factor with proper design |
Generally not a Factor |
Not a Factor |
Not a Factor |
NA |
NA |
Generally low, only routine inspection required of all
components |
|
Cistern
|
Usually not a factor with proper design |
Not a Factor |
Not a Factor |
A factor in high water table areas for in, or on-ground
placement |
Usually not a factor with proper design |
Usually not a factor with proper design away from foundation |
NA |
Recommend a minimum of 100 Ft. |
Low to moderate requirements |
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(Source:
Texas Guide to Rainwater Harvesting)
The use of rain
barrels in urban and suburban areas, along with downspout
disconnection, is being encouraged in a number of jurisdictions
across North America. In the City of Toronto, Canada a city-wide
Rain Barrel Program was initiated in 1996 in which the residents
have access to free downspout disconnection by a City contractor.2
City residents, while not offered any direct financial incentives,
are told of the economic and environmental advantages rain barrels
and downspout disconnection will have for them, such as helping to
keep the beaches of Lake Ontario clean, as well as:
-
Saving them tax dollars by reducing or
delaying the need to expand or upgrade sewage treatment
facilities.
-
Helping to reduce the severity of
basement flooding caused by sewer back-up.
-
Saving money on their water bill by
providing free rainwater for lawn and garden use.
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