Dual piping is a system of plumbing installations used to supply both

potable Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, a ...

and

reclaimed water Water reclamation (also called wastewater reuse, water reuse or water recycling) is the process of converting municipal wastewater Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produce ...

to a home or business. Under this system, two completely separate water piping systems are used to deliver water to the user. This system prevents mixing of the two water supplies, which is undesirable, since reclaimed water is usually not intended for human consumption. In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, reclaimed water is distributed in lavender (light purple) pipes, to alert users that the pipes contain non-potable water. Hong Kong has used a dual piping system for toilet flushing with sea water since the 1950s. According to the El Dorado Irrigation District in California, the average dual-piped home used approximately of potable water in 2006. The average single family residence with traditional piping using potable water for irrigation as well as for domestic uses used between , higher elevation, and , lower elevation.

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