THE BUILDING & PLUMBING BULLETIN

The American Southwest has been experiencing higher than average temperatures and increasing drought. With increasing percentages of land experiencing extreme drought conditions, water allocation becomes increasingly contested. Even though some areas of California received double the average precipitation from January to March 2017 and there has been extreme flooding, much of the water does not reach the aquifers, which would provide increased water security, as natural aquifer recharge is a slower process. Californians have made changes in their water consumption, but the stability of water resources still requires careful attention. The continued threat of water scarcity could encourage people to seek further water savings, including onsite water reuse.

The International Residential Code (IRC), International Plumbing Code (IPC), Uniform Plumbing Code (UPC) including the State of California plumbing code, and International Green Construction Code (IgCC) all require water reuse systems to meet the requirements of NSF/ANSI 350: Onsite Residential and Commercial Water Reuse Treatment, which establishes criteria for water reuse system material, design and performance. NSF/ANSI 350 certified systems can also earn credits during LEED certification. The standard has residential and commercial categories for systems that treat graywater (such as water from residential laundry or bathing) and combined black and graywater. The treated water can then be used for non-potable activities, such as toilet flushing and irrigation. Onsite water reuse systems reduce greenhouse gas emissions and water needs.

As California continues to champion statewide sustainability, including reducing greenhouse gas emissions, onsite recycling of graywater could allow homeowners to participate in this initiative. A study by the Pacific Institute determined that there could be net energy savings with onsite residential reuse of graywater, even if household energy use increased.

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