Septic System Regulations in Washington

In Washington, onsite wastewater (septic) systems are regulated by Washington State Department of Health (DOH), Environmental Public Health Division — Wastewater Management Program, which sets the statewide code, and permits are issued and inspections carried out by county or local health jurisdictions. Installing, replacing or repairing a septic system here means, in sequence: a site and soil evaluation, a design, a permit application, an inspection while the system is open, and a final as-built record once it is approved.

Who regulates septic systems in Washington

The state-level regulator is Washington State Department of Health (DOH), Environmental Public Health Division — Wastewater Management Program (official program page). The Washington State Board of Health adopts the statewide on-site sewage system code (WAC 246-272A), and DOH provides technical support and runs a separate Large On-site Sewage System (LOSS) program, but local health jurisdictions (city/county health departments) administer permitting, site evaluation, inspection, and enforcement for individual septic systems.

The statewide onsite-wastewater code is cited as WAC 246-272A (On-site Sewage Systems). We link the agency's own page above rather than restating specific numeric requirements from it, since those change by rule revision and by local amendment.

The permit sequence

The order of operations is broadly consistent across the country, even though the specific numbers in each step vary by state and often by county. None of the figures below are specific to Washington; treat this as the shape of the process, and get the actual numbers from the agency linked above or from the county office.

1. Site and soil evaluation. A qualified evaluator (see licensing below) digs test pits or runs a percolation test, and records the soil profile, depth to seasonal water table, depth to any restrictive layer, and slope. This determines whether the lot can support a conventional system or needs an alternative design.
2. Design. Under most state codes, daily design flow is set from bedroom count, not square footage. That flow drives tank capacity, and the soil evaluation sets the drainfield application rate and therefore its size. The designer also lays out setbacks to wells, property lines, surface water, foundations and a reserve/replacement area.
3. Permit application. Submitted to whichever office issues permits here (state agency or county/district health office, per the delegation model above), along with the design and soil work.
4. Installation and open inspection. The installer builds the system, and it is inspected before backfill while it is still open to view.
5. As-built and approval. A final drawing of what was actually built is filed once the system is approved. That as-built is the document a future owner, pumper or inspector needs, and it is what ends up in the county record.

Who can design and install a septic system

Getting septic records in Washington

Records requests in Washington are governed by the Chapter RCW 42.56 (Public Records Act), which sets a response deadline of 5 business days.

Fees: Bulk electronic ask is far cheaper than per-page scans; ask for the index/db export first.

Counties in Washington we hold records for

We hold 1,059,156 septic records across 29 of 39 Washington counties. Each county page below shows exactly where its records are kept and how many we hold.

Full Washington county-by-county index · Open the parcel map

Common questions

Who regulates septic systems in Washington?

Washington State Department of Health (DOH), Environmental Public Health Division — Wastewater Management Program. The Washington State Board of Health adopts the statewide on-site sewage system code (WAC 246-272A), and DOH provides technical support and runs a separate Large On-site Sewage System (LOSS) program, but local health jurisdictions (city/county health departments) administer permitting, site evaluation, inspection, and enforcement for individual septic systems.

What is the septic permit process in Washington?

The sequence is a site and soil evaluation, a design sized from the evaluation and (under most state codes) bedroom count, a permit application, an inspection before backfill, and a final as-built filed once the system is approved. Exact numeric requirements are set by the agency's own code, not restated here.

Who can install a septic system in Washington?

Installers, pumpers, and maintenance providers are certified by the local health jurisdiction (e.g., Associate/Master Installer certification); there is no single statewide installer license and requirements vary by county.

How do I get septic records for a property in Washington?

Records requests are governed by the Chapter RCW 42.56 (Public Records Act), with a 5 business-day response deadline. Records themselves are generally filed at the county or district office that issued the permit, not the state agency; see the county's page for that county's specific portal or contact.

Sources

• https://doh.wa.gov/community-and-environment/wastewater-management
• https://doh.wa.gov/community-and-environment/wastewater-management/site-sewage-systems-oss
• https://lawfilesext.leg.wa.gov/law/WACPDF/WAC%20246%20%20TITLE/WAC%20246%20-272A%20CHAPTER/WAC%20246%20-272A%20COMBINEDCHAPTER.pdf
• https://kingcounty.gov/en/dept/dph/health-safety/environmental-health/on-site-sewage-systems/resources-for-sewage-septic-professionals/certifications

Regulatory information on this page was researched against official state agency sources and last verified 2026-08-31. It is informational only: the agency linked above is authoritative, and requirements can change. We are not lawyers, not a government body, and not affiliated with, licensed or certified by any agency named on this page.