Regulations prohibit graywater systems from being connected to potable water systems and do not allow surface applications of graywater. Instead graywater must be released below the surface, as underground landscape irrigation, to prevent human contact with it. Many advocates claim the regulations are needlessly complex, and the expense is a deterrent to graywater use. Despite regulatory requirements estimates indicate that there are several thousand graywater systems in the metropolitan area, and virtually none are permitted. Some residents merely drain their washing machines to water their shrubs or trees.
Some researchers question whether graywater really poses a significant health risk.
If the health risks are not as high as some fear, graywater might gain more acceptance as a water source, and regulations could be eased. Figure 3-14 Cistern installed as part of a graywater reuse system. The intent of the study is to raise public awareness, provide information not available elsewhere regarding graywater quality and its effect on soil, collect data on actual, feasible residential graywater system design and determine the potential graywater has to increase water use efficiency. Rainwater harvesting is collecting rainfall to meet water needs. A rainwater harvesting system concentrates and collects rain falling on house roofs and grounds for direct use and storage.