But rapidly draining water off landscapes rather than allowing it the time and space to soak in causes a host of problems downstream and in the pipes. Culverts pour water into gullies and seasonal creeks, overloading and eroding the natural drainage area and rushing sediment into rivers, streams and estuaries, where it imperils fish.
Downspouts, gutters and sloping driveways conduct water into the storm water and sewer systems, which can dump raw sewage when overloaded. After we’re finished draining our properties, we pay, increasingly dearly, to pipe water back into our homes and landscapes.
Dolman advocates replacing the “drain age” with a new “retain age,” wherein we capture and store storm water for future use and resculpt yards and gardens to allow water to percolate into the ground.
To take a step into the retain age, consider harvesting rainwater from your roof and banking more water in your soil.
Harvesting roof water
Every inch of rainfall on 100 square feet of roof surface yields 55 to 60 gallons of water. For a 2,500-square-foot home, that translates to 1,375 to 1,500 gallons of water per inch of rain. This water can be caught and stored in above- or belowground cisterns and used for drinking, in-house nonpotable uses or irrigation, depending upon what filtration systems are installed and upon local regulations.
For information on roof water harvesting systems, go to:
— www.arcsa.org: The American Rainwater Catchment Systems Association Web site features links to a wide range of rainwater harvesting resources. Click on Resources to see the list.
— links.sfgate.com/ZFOA: This page links you directly to the ecology center’s list of articles and books on the subject.
— links.sfgate.com/ZFOB: A “Renewable Energy Site for Do-It-Yourselfers” with links to information on roof water harvesting systems.
If installing a roof water cistern seems too daunting, consider cutting off the bottom of a downspout and sliding a rain barrel under it to catch a portion of the water falling on your roof. Use the water to irrigate your garden during dry periods between storms.
Several sites provide information on rain barrels:
— links.sfgate.com/ZFOC: The San Francisco Public Utilities Commission’s Web site has information on the commission’s recently launched program to help San Francisco residents purchase rain barrels at a discounted price.
— links.sfgate.com/ZFOD: A good description of how to build a rain barrel from the Maryland Department of Natural Resources.
— links.sfgate.com/ZFOE: Find rain barrel as well as roof water harvesting information on this “Renewable Energy Site for Do-It-Yourselfers.”