Rainwater Harvesting

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Rainwater harvesting is one way to maximize the use of water on your property. Currently there are no rules that spell out how and when rain water can be used. Guidelines are being established by the County of Los Angeles Public Health Department in 2009. Check with your local building or planning department before installing a system.

What is rainwater harvesting?

Rainwater can be collected from any surface and stored to allow use at a later time for non-drinking water applications such as watering lawn and plants.

•	A cistern is a catchment device to capture rain water from a roof or other surface before it reaches the ground. A cistern is connected to an irrigation system.

•	Rain barrel is a smaller catchment device to capture and store rain water from a roof or other surface. Rain barrels typically have a spigot where you can attach a garden hose.

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Infiltration pit is a hole in the ground that’s filled with rock or other material to allow rainwater to percolate deep into underground aquifers. The gutters from the roof are plumbed into the pit. The rainwater is not reused on-site for irrigation but recharges our drinking water aquifers. To find out more visit www.sustainablesm.org/runoff.

Deidra Walpole rain chain 2

How much water can I collect?

That depends on the size of your roof or collection surface, the size of the cistern or rain barrel, how much it rains and how much water is currently in your barrel or cistern.

Multiple the square footage of roof space you have available X 0.6 gallons per square foot per inch of rain, and you can see how much water you can collect from each inch of rain that falls.

So if you have 2,500 square feet of roof available for water catchment, and a single inch of rain falls one day, you can collect: 2,500 square feet X 0.6 gallons X 1 inch = 1,500 gallons of rainwater

Websites:

•	The American Rainwater Catchment Systems Association is a great place to learn about cisterns: http://www.arcsa-usa.org.

•	http://www.harvesth2o.com/

•	www.sustainablesm.org/runoff

Infiltration Pits

For information on Infiltration Pit Retention Fillers, please go to: http://www.smgov.net/uploadedFiles/Departments/OSE/Categories/Urban_Runoff/UR_Infiltration_Pit.pdf