Components of a Rainwater Harvesting System
• Capturing the rainwater
• Storing
• Filtering
• Emergency use
• Distribution for irrigation and/or designated use
Catchment Surface:
Most roof surfaces are acceptable. Roofs with smooth surfaces, like metal and concrete tile, are best for durability and rainwater quality. For a tar and gravel roof or cedar shingle roof impregnated with fire retardant, we typically recommend other roofing solutions for a rainwater system. Solar panels are also ideal catchment surfaces and are increasingly integrated into rainwater systems.
Gutters and Downspouts:
Gutters catch rainwater that is then diverted into downspouts where rain can be channeled into storage tanks. We recommend pre-filtration components to initially remove large particulates.
Leaf Screens, First Flush Diverters, or Roof Washers:
Leaf screens, first flush diverters or roof washers are pre-filtration components to ensure the storage of the highest quality water. The leaf screens remove large particulates such as leaves and branches, while the first flush diverters and roof washers reduce accumulated small particles from entering the storage tank.
Storage:
Above Ground - There are many different size and shape tanks for above ground use. The most common types of storage tanks are: polyethylene, corrugated metal, concrete and Ferro cement and a wide variety of rain barrels.
Underground - There are also solutions to storing water below ground. Underground tanks or modular units can be linked together, to serve as a void space to collect and store water and covered with impermeable material. Used most often if space is limited.
Distribution:
There are energy efficient and easy-to-use pumps on the market perfect for rainwater applications. Commonly, when irrigation is desired -- a pump can be used to transfer and pressurize the water. Gravity flow usually does not provide adequate pressure for most irrigation systems unless there is a large elevational difference. For example, a 50-foot elevation is necessary to obtain a pressure of 20 pounds per square inch (psi).
Treatment and Purification:
Typically rainwater is filtered one more time before the point of use as a precaution to ensure proper irrigation system function.
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