Steve and I had met several times over the past few years at Rainwater Harvesting and Water Conferences. We had a good connection and both of us are passionate advocates for sustainable energy projects. He and his client set a high standard – Net Zero Water use on a moderately sized residential lot in Los Altos, CA. In order to create a program to achieve this we had to quantify how much rainwater the site would provide for the various uses – interior as well as exterior. Then, we had to look at the existing amount of water the client normally uses. In this aspect, I determined that their current water use, especially for irrigation was very excessive. This is typical for most landscapes as clocks are set on automatic and the mantra is “give it more water so it will stay green”! Unfortunately, this is a huge, uneducated, and supremely wasteful approach. Remember that here in California, at the residential level about 50% of the water that goes thru a household goes to irrigation. In this instance approximately 76% went to outdoor usage (see Van Buren Water Balance Model 2010–provided by RainSpace). So, one of the main routes to success was to cut irrigation substantially and provide the mechanisms to very smartly and efficiently irrigate the new plant scheme, as designed by Kikuchi and Associates. Additionally, more conservation in household use would be required. Fortunately, client and family are willing cut back – not a lot, but enough to make the water budget balance. Furthermore, by utilizing graywater in the irrigation system we could save approximately 40,000-50,000 gallons of potable water, thereby saving the City pumping and water treatment costs – very important as it relates to energy consumption and a macroview of the water/energy situation. In addition to utilizing the graywater we have designed in an underground capillary irrigation system which will wick up the gray and rainwater as the plant roots go down. As a final touch, we are incorporating a moisture sensor in certain landscape areas (lawn especially), that will help calibrate the amount of water moving thru the underground sand strata which will be the base of the family lawn. There will also be a flow meter to quantify how much water goes thru the system.
