Gray water, or greywater, is wastewater generated from a variety of sources in homes and commercial buildings through the use of water for showers, washing machines, bathroom sinks, dishwashers, or other uses.  Greywater does not contain serious contaminants and does not include water from toilets or urinals.  The Department of Health is responsible for developing standards, procedures, and guidelines, with input from technical experts, for cost-effective reuse of greywater.
 
Nonpotable water is water that is not of drinking quality, but may still be used for many other purposes, depending on its quality.  Nonpotable water is generally all raw untreated water, such as from lakes, rivers, groundwater, natural springs, and ground wells.  Nonpotable water sources also include rainwater, reclaimed/recycled water, and greywater.  While nonpotable water is not appropriate for human consumption, it can be used in other applications, such as doing laundry and toilet flushing.
 
On-site nonpotable water reuse systems capture and treat water sources generated from within, such as wastewater, greywater, stormwater, or roof collected rainwater.  The treated water is then reused onsite or locally for nondrinking purposes.

The Department of Health (DOH) is required, in consultation with the Washington State Building Code Council (SBCC) and the Washington State Association of Plumbers and Pipefitters, to adopt rules by July 1, 2022 for:

• risk-based water quality standards for on-site treatment and reuse of nonpotable alternative water sources for nonpotable end uses; and
• construction standards to adopt the risk-based framework water quality standards.

 
At minimum, the adopted rules must address:

• risk-based log reduction targets for removal of pathogens for alternative water sources, including wastewater from all domestic fixtures, gray water, rainwater, and stormwater for nonpotable end uses such as toilet and urinal supply water, clothes washing, irrigation, and dust suppression;
• treatment and performance requirements;
• water quality monitoring requirements;
• reporting requirements for the treatment, performance, and water quality monitoring results;
• notification and public information requirements;
• cross-connection controls;
• permitting; and
• any conflicts the rules may have with the Department of Ecology's (Ecology) municipal stormwater general permit and guidance manuals on stormwater for eastern and western Washington.

 
Any calculations in the amount of water a property owner or permit holder must make to address runoff from impervious surfaces must reduce the amount of rainwater considered to be stormwater when it is captured to be used for alternative nonpotable end uses in buildings and projects.
 
The rules take effect December 31, 2022.  If any on-site treated nonpotable water systems are in operation before January 1, 2022, then such systems must be in compliance with the rules by January 1, 2024.
 
The permitting local jurisdiction may grant a permittee a waiver of compliance with the rules if the local jurisdiction finds the permittee is unable to come into compliance with the rules because the engineering, repair, or replacement of the system is cost prohibitive.
 
DOH may consult or contract with other public or private entities, including the SBCC and Ecology, for advice on state building code language, water rights, water quality, and other technical matters relating to adoption of the risk-based water quality standards.