Onsite Nonpotable Water Systems Rulemaking

What's Happening?

The Department of Health (Health) is developing rules to allow for the on-site treatment of nonpotable water systems (ONWS). The treated nonpotable water can then be used onsite where potable (drinking water) isn’t needed.

These rules would apply to multifamily residential, commercial, and mixed-use buildings, and district-scale projects including a mix of multifamily residential, commercial, and mixed-use buildings. Water sources include wastewater from all domestic fixtures, gray water, rooftop runoff, stormwater, foundation drainage, and AC condensate. Water treated to the established risk-based water quality standards may be used for end uses such as toilet and urinal flushing, irrigation, and dust suppression.

On April 4, 2024, the department withdrew the original CR-101 filed in August 2021 (PDF) by filing a withdrawal memo (PDF) with the Code Reviser. Initially the department anticipated the rule making would only set risk-based water quality and construction standards. However, during consultation with the ONWS rule advisory committee it became clear that if the ONWS chapter was more comprehensive and included more than the risk-based water quality and construction standards we could better ensure statewide consistency and reduce the regulatory burden on small businesses, designers, engineers, installers, and local health jurisdictions.

Also on April 4, 2024, the department filed a new CR-101 (PDF) with a broader scope to allow for the development a more comprehensive and equitable ONWS rule.

If you have any questions or would like to discuss the ONWS rulemaking, contact Jocelyn Jones.


As water supplies become more strained, climate change persists, and populations grow, communities are looking for new ways to develop, diversify, and manage local water supplies and increase the resiliency of community water infrastructure. On-site nonpotable water treatment RCW 90.46.290 was enacted in 2021 requiring us, in consultation with the state building code council and the state association of plumbers and pipefitters, to adopt rules for ONWS. ONWS present a new treatment option that can reduce the need for potable water where potable water is not needed.

Get Involved!

A Rules Advisory Committee (RAC) comprised of impacted agencies and interested parties, including Department of Ecology, State Building Code Council, Washington State Association of Plumbers and Pipefitters, local health jurisdictions, municipalities, and design consultants has been working to draft rules.

Contact Jocelyn Jones, Rules Coordinator, if you would like to participate in the RAC.

RAC Meeting Date Link
October 12, 2021 Presentation Slides
October 18, 2021 Presentation Slides
April 21, 2022 Presentation Slides

Review the draft rule! Use these resources to help with your review.

Resources for Onsite Non-Potable Water Programs

Video segments explaining each part of the ONWS rule.

Rulemaking Files

Document What's This? Date Filed
CR-101 (PDF) Announces intent of rulemaking August 9, 2021
CR-101 Withdrawal Memo (PDF) Serves as notice that the original CR-101 was withdrawn April 16, 2024
CR-101 – 2nd filing (PDF) Announces intent of rulemaking April 16, 2024


Jocelyn Jones, Reclaimed Water Policy Lead, 360-999-3662

Steve Deem, Subject Matter Expert, 253-395-6767

Mamdouh El-Aarag, Subject Matter Expert, 509-329-2148

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