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On-site sewage system code revision process
This year, King County is revising the codes (rules) that govern on-site sewage systems (OSS). We are doing this to comply with recent changes to state law. We’re also using this opportunity to improve the codes and incorporate the latest best science.
Read the proposed codes
Based on technical and legal analysis, equity review, feedback from our customers and partners, community input, and public comment, we are proposing code changes to the King County Board of Health.
Proposed code language
- Proposed rule and regulation: BOH Title 13, On-site Sewage Systems (1.2 MB)
This is the document that the Board of Health will vote on to adopt code revisions. It includes only the Title 13 sections that are changing. - Full BOH Title 13 language with proposed changes (587 KB)
This document is the full Title 13, including sections with and without proposed revisions and proposed new sections.
More information about the code process
Frequently Asked Questions
No, if your septic system is functioning, no upgrades are necessary. The code changes make small changes to processes that already exist for septic system permitting and maintenance, so the only times when the new code revisions might impact an existing septic system is during a permitting or maintenance activity.
For example, one of the proposed changes is to require that all septic tank lids be secured to prevent risks of kids or pets falling into the tank. If this change goes into effect, the maintainer who next inspects your septic system would need to make sure that the lids are secured during that inspection.
No annual fee is being proposed. When this was proposed in 2016, we heard from community members that this was not a good idea, so we did not even consider proposing it as part of these code revisions.
No, Health Department inspectors do not go onto your property without your permission.
No, a septic system failure can be caused by many different things. If the tank or smaller parts of the septic system are broken, those can be easily and quickly fixed. The biggest failure is when the drainfield stops working. If this happens and your septic tanks are still holding water, you can use the same tanks in a new septic system replacement.
Next steps
The King County Board of Health will hear a briefing on the proposed revisions during its January meeting and vote during the February meeting. More information about the meetings will be available on the King County Board of Health website.
Background
In early 2024, the Washington State Department of Health approved new OSS codes. Since then, we have worked to figure out how to incorporate the state's changes into our local codes (our local codes are required by law to be at least as restrictive as the state's codes).
In early June, we launched a website and survey with proposed code revisions, in order to get public feedback. Over the course of this summer, we hosted 13 public meetings and received hundreds of comments.
In September, we released draft proposed changes to the codes for public comment. We met with and heard from hundreds of King County residents at six public comment meetings and through our public comment survey about the proposed language. We’ve reviewed public comments and finalized the proposed revisions for submittal to the Board of Health. Next, we’ll present the proposed changes to the Board of Health for their review.
Key steps in the code revision process
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March 2024
State Board of Health finalizes revised OSS codes.
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May – October 2024
King County public engagement period - change to comment on possible local code revisions.
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January – February 2025
King County Board of Health reviews and votes on local code revisions.
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April 2025
Revised local codes go into effect.