Sourced from the State Water Resources Control Board OWTS Policy update documentation and Resolution 2023-0012 — last checked August 2026.
Why the Policy Gets Amended At All
This surprises people who assume the 2013 rules still stand unchanged.
The OWTS Policy contains a conditional waiver of waste discharge requirements for systems that comply with it. Under California Water Code section 13269, such waivers expire after five years.
So the State Water Board has to renew it periodically, and each renewal is an opportunity to update the Policy. That has happened twice:
| Event | Date |
|---|---|
| Policy adopted (Resolution 2012-0032) | June 19, 2012 |
| Approved by the Office of Administrative Law | November 13, 2012 |
| Effective | May 13, 2013 |
| First renewal (Resolution 2018-0019) | April 17, 2018 |
| Second renewal (Resolution 2023-0012) | April 18, 2023 |
| Next renewal due | Effective May 13, 2028 |
⭐ The Change That Affects Homeowners
Tier 3 carries supplemental treatment, monitoring and oversight requirements — the most expensive designation in the California framework. Some water bodies came off the list in April 2023 because technical studies and other factors justified the change.
If you were told at some point that your property was in a Tier 3 area, it’s worth re-checking. That designation may have lapsed, and nobody would necessarily have told you.
The practical step: contact your county environmental health department and ask whether the water body near your property is still listed, and whether the county has an APMP covering your area.
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Which OWTS Tier Are You Under?
California’s OWTS Policy sets five tiers, and which one applies decides your siting standards, your flow ceiling, whether supplemental treatment is required, and whether you can add an ADU. The state publishes the framework but nothing that tells a homeowner where they land.
Directional guidance based on the State Water Board OWTS Policy and its published regional jurisdiction list. Your local agency makes the actual determination, and an approved Local Agency Management Program can set standards that differ from the statewide defaults. Confirm with your county before relying on this.
The Other Changes
New definitions added. The amendment defined Domestic wastewater, Accessory Dwelling Units (ADUs), CWSRF (the Clean Water State Revolving Fund), and LAMP.
The ADU definition is the notable one. Adding it to the Policy formalizes what had been guidance, and it arrived alongside California’s broader push to make ADUs easier to build. See our ADU guide.
Agency references updated. References to the California Department of Public Health were replaced with “State Water Board” — a housekeeping change, but useful if you’re reading older documents that name a department no longer involved.
Tier 2 clarified. The amendment clarified that differing system design requirements under a LAMP may include alternative collection and disposal systems that use subsurface disposal. In plain terms, it gave LAMP counties more explicit room to approve non-conventional designs.
LAMP reporting cycle changed. The five-year water quality assessment reporting period was revised from “five years after each LAMP’s approval date” to a fixed five-year cycle beginning in 2018. That’s an administrative change affecting counties rather than homeowners, but it means all LAMP counties now report on the same schedule.
Why Most Guidance Hasn’t Caught Up
Policy amendments don’t generate much coverage. A resolution number and a board meeting date aren’t news, and content written from older sources inherits the older picture.
The result is a lot of California septic guidance that describes the Policy as it stood in 2013, and occasionally as it stood in 2018 — without noting that the impaired waters list has since changed and that some properties came out of Tier 3 as a result.
Worth knowing the framework runs on a five-year cycle. The next renewal takes effect May 13, 2028, and the list could change again.
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Frequently Asked Questions
When was the OWTS Policy last amended?
April 18, 2023, under Resolution 2023-0012. It was previously amended April 17, 2018. The policy took effect May 13, 2013.
Why does the OWTS Policy keep getting renewed?
It contains a conditional waiver of waste discharge requirements, and under Water Code section 13269 such waivers expire after five years. Each renewal is an opportunity to update the policy. The next renewal takes effect May 13, 2028.
What changed for homeowners in 2023?
Some water bodies were removed from the impaired waters list. Systems near a removed water body are no longer subject to Tier 3 requirements unless the local agency has developed an advanced protection management program for the area.
What definitions were added in 2023?
Domestic wastewater, Accessory Dwelling Units, CWSRF (Clean Water State Revolving Fund), and LAMP (Local Agency Management Program).
How do I find out if my property is still in a Tier 3 area?
Call your county environmental health department and ask whether the water body near your property is still listed, and whether the county has an APMP covering your area.