Wholly H2o - California's Integrated Water Reuse Management Center

"Rainwater harvesting" (RWH) and “stormwater catchment” are often used interchangeably referring to a wide range of practices that capture and utilize or infiltrate rainfall on a site, rather than funneling it into storm drains.

Rainwater Harvesting (RWH) is the practice of capturing, infiltrating or utilizing rainfall from roofs, constructed catchment surfaces, and driveways, sidewalks, parking lots and streets.

On the water supply side, harvesting rainwater (and graywater) will great reduce your demand for municipally treated potable water, well water, and other water sources generally tapped for daily needs, regardless of scale.

Even when using captured rainwater, get in the habit of using water wisely. Many existing homes, commercial, institutional and industrial facilities will save significant water and money by repairing leaks and installing high-efficiency fixtures where water is used.

Every RWH system is custom tailored to site features, intended water use, budget, new construction or a retrofit, and other factors.

Whether you are a homeowner, a water manager for a large industrial campus or a farmer trying to collect water for irrigation or animal watering stations, there are some common features to RWH systems. RWH systems typically break down into: Collection, Filtration, Storage, and Distribution.

Rainwater falls as a very pure water. Factors that can compromise its quality are contaminants picked up from the air, contaminants that have settled or fallen onto collection surfaces, and the physical properties of the collection surfaces and system components themselves.

As of late 2009, California had no statewide regulations that either permit or prohibit rainwater harvesting. It is best to check first with your city and/or county regarding codes and ordinances for RWH system installations.

Costs for RWH systems vary tremendously, depending on the scale and complexity of the system. A simple residential rain barrel system for gravity-fed irrigation put together by the homeowner could cost as little as $200.