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Harvesting Rainwater and Using Graywater

You can lower your water bills by collecting rainwater and using it to water plants. An added benefit of rainwater harvesting is that it reduces the risk of flooding and erosion and decreases the volume of rainwater flowing into storm drains and carrying pollutants into our urban watershed.

You can also conserve water by diverting graywater from your home’s plumbing system to landscaped areas. Graywater is simply waste water that is not contaminated with human waste; it includes waste water from bathroom sinks, showers, bathtubs and clothes washing machines. It is not suitable for drinking, but it can be piped outside and used for subsurface irrigation of the roots of trees and shrubs. 

Tips for rainwater collection and graywater reuse:

  1. Harvest rainwater. A common way to do this is to channel rainwater from the roof through gutters and downspouts to barrels, cisterns or other rainwater storage containers. You can then use the stored water for irrigation during dry spells. 
  2. Create rain gardens. These are shallow depressions planted with native plants and grasses that can tolerate periodic inundation. You can channel rainwater from downspouts to rain gardens so that it slowly sinks into the soil rather than running off the property.
  3. Plumb your home for graywater reuse. The websites listed below have helpful info about do-it-yourself graywater options as well as more advanced plumbing work that may require the services of a plumber. If you have a graywater system, be sure to use biodegradable soaps and don’t put any substances down the drain that might harm plants or soil organisms.
  4. Slow the flow of stormwater runoff. You can passively harvest rainwater simply by minimizing impervious surfaces such as asphalt or concrete driveways, walkways and patios. Use porous surfaces, including permeable paving, and maximize landscaped areas to encourage infiltration of rainwater into the soil.

For more information about rainwater harvesting and graywater use, check out these websites: