Water conservation is an important concern in many parts of the country and so technology for recycling water is expanding. It is estimated that homeowners waste an average of 33 percent of the available drinking water every day, using it for landscape irrigation (Coder, 2001). Slightly used water is known as gray water, and can be used as a landscaping and agricultural water supply, and also for flushing toilets. It is not safe to drink gray water (Jett, 2001). Across America, toilet flushing and landscape watering are the major home uses of drinkable water. Black water, water from sewage, cannot be used for these purposes.
In 1992, the Los Angeles Office of Water Reclamation looked at using gray water for irrigating gardens and found there was no greater health risk associated with the use of below-ground gray water irrigation than with conventional watering methods (Hefger, 1993). They evaluated a pilot gray water program undertaken by the city which was later extended to the state and noted that the water savings potential of a gray water system to an individual home could be as much as 50 percent of all the water used. It is estimated that a family of four, producing 1,652 gallons of gray water per week will produce enough water to irrigate a yard consisting of 900 square feet of lawn, 10 mature fruit trees, nine large shade trees and 15 large shrubs.
Gray water can be used a second time (Coder, 2001). It includes water from sinks (but not those with garbage disposals attached), dishwashers, bathtubs, showers and water used in washing machines or for hand laundry. According to the California Administrative Code, gray water does not include waste water from kitchen sinks, photo lab sinks, dishwashers or laundry water from soiled diapers (Appendix G: Gray Water Systems, 2001). If this gray water is used, it can almost double home water-use efficiency as well as provide water for irrigating the garden. Using gray...