Onsite Nonpotable Water Systems Rulemaking

This past spring, the Department of Health (DOH) received many informal comments and suggested edits to a draft of a new chapter for on-site nonpotable water systems (ONWS), chapter 246-275 WAC.

We have considered these comments and we have updated the draft to reflect many of the comments. 

Updated Draft Rule Language  

Updated Draft Rule (Word)

  • Track your suggested edits, insert your comments, rename the file with your name, and save your file locally while you work. 
  • Email the renamed file with your tracked edits and comments to Jocelyn Jones by July 28, 2023. 

ONWS Rule Overview Presentation Videos 

Videos based on the earlier draft (Word) but are still relevant and useful.

The following video segments provide an overview of each part of the draft rule to help you with your review. We suggest following along in the draft rule language while watching the presentation segments, pausing when you need to comment or suggest an edit. 

Purpose of the ONWS Rulemaking

DOH is considering adopting a new rule chapter (Chapter 246-275 WAC, Onsite Nonpotable Water Systems) to implement RCW 90.46.290 On-site nonpotable water systems.

This amendment to existing statute requires the department of health to establish risk-based water quality standards for the onsite treatment of nonpotable alternative water sources for nonpotable end uses. In addition, it requires establishment of construction standards to achieve these water quality standards.

The CR-101 Preproposal Statement of Inquiry (PDF), announcing our intention to begin rulemaking, was filed on August 9, 2021 and recorded as WSR 21-17-040 (PDF).


The Onsite Nonpotable Water Systems (ONWS) rule 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. Alternative 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 supply water, clothes washing, irrigation, and dust suppression.

Public Involvement 

DOH has engaged in collaborative rulemaking in consultation with impacted agencies and stakeholders, including the Washington State Department of Ecology and the state Building Code Council. Other interested parties include representation from the Washington State Association of Plumbers and Pipefitters, local health jurisdictions, municipalities, and design consultants. 

Model Code

A model code that was considered during this effort was developed by the National Blue Ribbon Commission for Onsite Nonpotable Water Systems. View the model regulation on the US Water Alliance's website.

Rule Advisory Committee (RAC)

DOH held RAC meetings in October 2021 and April 2022. Based on feedback from the RAC, we have drafted rule language we hope addresses this capacity issue.  

October 12, 2021 - RAC Meeting Presentation Slides (PDF)

October 28, 2021 - RAC Meeting Presentation Slides (PDF)

April 21, 2022 - RAC Meeting Presentation Slides (PDF)

Stay Informed

Rulemaking notices will be sent to various general interest and environmental public health lists. To receive notices, sign up for the Onsite Nonpotable Water Systems Rulemaking email list.

Rulemaking Contacts

Steve Deem, subject matter expert, 360-878-7625

Mamdouh El-Aarag, subject matter expert, 509-329-2148

Jocelyn Jones, project co-manager, 360-236-3020