1. Defined by the Uniform Plumbing Code (UPC) in its Appendix G, titled"Gray water Systems for Single-Family Dwellings,"as"untreated household wastewater which has not come into contact with toilet waste. Grey water includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs. It shall not include wastewater from kitchen sinks or dishwashers."2. The International Plumbing Code (IPC) defines graywater in its Appendix C, titled"Graywater Recycling Systems,"as"wastewater discharged from lavatories, bathtubs, showers, clothes washers, and laundry sinks."Some states and local authorities allow kitchen sink wastewater to be included in graywater. Other differences with the UPC and IPC definitions can probably be found in state and local codes. Project teams should comply with the graywater definitions as established by the authority having jurisdiction in their areas.