What's Happening?
The Department of Health (department) 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.
On August 4, 2026, the department filed proposed rules to establish general administrative procedures, treatment and performance requirements, allowable source water, end uses and implementation scales, design and construction standards, monitoring, reporting, and recordkeeping requirements, as well as operation and maintenance requirements for ONWS. The proposed rules also establish procedures for enforcement and violations, as well as set fees.
If you have any questions or would like to discuss the ONWS rulemaking, contact Kseniya Efremova.
Why?
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!
Provide Comments
The department invites you to comment on the proposal through September 22, 2026, at midnight. A virtual public hearing will be held on September 22, 2026, beginning at 11:00 am to give you an opportunity to provide oral comments.
If you wish to attend the public hearing, please register on Zoom.
After registering, you will receive a confirmation email containing information about joining the webinar.
Written comments can be sent through email to kseniya.efremova@doh.wa.gov or may be submitted online at the department’s rules comment page.
Please note that all comments received, whether by email or online, will be given the same consideration. We encourage you to comment in a manner that is most convenient for you.
Proposed Rule Documents
- CR-102: Proposed Rule Making with Proposed Rule Language (PDF)
- Significant Analysis (PDF)
- Small Business Economic Impact Statement (PDF)
- Economic Impact Analysis (PDF)
Resources
Rules Advisory Committee Meetings
- October 12, 2021 Presentation Slides (PDF)
- October 18, 2021 Presentation Slides (PDF)
- April 21, 2022 Presentation Slides (PDF)
Resources for Onsite Non-Potable Water Programs
Videos
Video segments explaining each part of the ONWS rule. Note: These video segments reflect an outdated version of the draft rule language.
- Introduction to rulemaking
- Part 1: General provision
- Part 2: Planning, review, approval, and permitting process
- Part 3: Design, Log10 reduction targets and credits, and water quality limits
- Part 4: Operations
- Part 5: Monitoring, reporting, notification, and recordkeeping
- Part 6: Compliance and enforcement - Part 9: Fees
Tentative Rulemaking Timeline
- August 2021 – Start rulemaking
- February 2023 – First informal comment period
- April 2024 – Withdraw original CR-101, file new CR-101
- September 2025 – Second informal comment period
- September 2026 – Formal comment period and public hearing
- October 2026 – Rulemaking complete
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 |
| ONWS Rule Language for Informal Public Comment (Word) | Draft changes for informal public comment period. Comments are due by October 8, 2025. | |
| CR-102 – Proposed Rulemaking (PDF) | Announces proposed permanent rulemaking. | August 4, 2026 |
| Significant Analysis (PDF) | Cost-benefit analysis that demonstrates that the agency has fully considered the need for the rule and has selected the rule as the best alternative to ensure public health and safety. | |
| Small Business Economic Impact Statement (PDF) | Analysis of the compliance costs of the rule and its impact on small businesses. | |
| Economic Impact Analysis Fee Report (PDF) | Summary of how the department determined new fees for ONWS. |
Contacts
Kseniya Efremova, Rules Coordinator, 360-236-3449
Mamdouh El-Aarag, Subject Matter Expert, 509-329-2148
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