Critical Review: Present Onsite Graywater Reuse Regulatory Incentives and Impediments in the United States

Graywater reuse has been identified as a potential water source for reducing water demand. Accordingly, a review of graywater reuse regulations/guidelines within the fifty United States was undertaken. Major issues considered included acceptability for segregation of graywater as a separate wastewater stream, allowable graywater storage, onsite treatment requirements, and permitted graywater use applications. Existing regulations and plumbing codes, among the different States and within States, suggest that there are impediments to overcome but also potential incentives for graywater reuse. It is encouraging that 29 States have regulations that promote safe graywater reuse, but there are also inconsisitencies between plumbing codes and other regulations within and among the fifty States. Impediments to graywater reuse include disallowances of graywater segregation or collection, and restriction of permitted graywater reuse to mostly subsurface irrigation with limited use permission for toilet flushing. In this regard, ease on restrictions and/or development of guidelines to promote development of low cost and proven treatment technologies are needed in order to promote graywater reuse.