How to Get a Septic Permit in Washington

Sourced from chapter 246-272A WAC (notably 246-272A-0230, 246-272A-0234 and 246-272A-0340), chapter 18.210 RCW, and the published fee schedules and application forms of Asotin, Spokane, Thurston, Tacoma-Pierce, Benton-Franklin, Grays Harbor, Whitman, Mason and Walla Walla health jurisdictions — last checked August 2026.

The sequence

Names differ between the 35 local health jurisdictions, but the order does not.

Step one decides your budget

🎯 The site evaluation is not a formality. It is the step that sets your cost, and it happens before you have committed to anything.

Table VI of WAC 246-272A-0230 takes two findings from that evaluation — your soil type and your vertical separation — and from them sets the treatment level and distribution method the rule will allow. Deep, well-drained soil permits a septic tank and a gravity drainfield. At the shallow end of the table you are required to install a higher treatment level with pressure distribution and timed dosing: a pump, a control panel, a dosing tank and a permanent electricity bill.

You do not choose which of those you get. The soil does. See what a septic system costs to install in Washington.

The evaluation fee itself varies more than any other line item: $95 in Asotin County, $790 in Kittitas. Thurston charges $615 for a standalone site evaluation, Mason $380, Grays Harbor $258, Whitman $300. Full county-by-county fees here.

🔴 Washington licenses the designer and the county approves the installer

This is backwards from most states and it catches people out.

• Designers are licensed by the state. Under chapter 18.210 RCW it is unlawful to design an on-site wastewater treatment system in Washington without a designer license or a professional engineer license under chapter 18.43 RCW. The licensing body is the board of registration for professional engineers and land surveyors.
• Installers are not state-licensed. WAC 246-272A-0340 requires installers — along with pumpers and maintenance service providers — to obtain approval from the local health officer before providing services. Approval can transfer by reciprocity from another Washington jurisdiction.

So “licensed and insured” on a van means different things for the two trades. Ask your designer for their state license number, and ask your health jurisdiction whether your installer is on its approved list. Since February 1, 2025 every jurisdiction has been required to run such a list; before then it was optional, so a firm operating legally in 2024 is not automatically approved now.

Some jurisdictions charge less to review a licensed designer’s work than a homeowner’s. Asotin, for example, charges $450 for a permit with a licensed designer and $650 where the homeowner designed it — a $200 gap that usually does not cover the difference in what a designer costs, but is worth knowing.

⚠️ The winter problem

🎯 Almost nobody mentions this, and it can cost you a building season.

The design depends on the highest seasonal water table, not the water table on the day someone dug a hole. Where a site is marginal, several jurisdictions require the soil to be observed during the wet season before a design can be approved — and they publish a fee for it:

If your site needs one and you apply in May, you are waiting for winter. Ask about it at the very start of the process, not after your design comes back. It is the single most common reason a septic timeline slips from weeks to months, and the fee is substantial in its own right.

The reserve area you must set aside

Your design has to identify a reserve area — land protected and kept available to replace the whole system when it eventually fails.

WAC 246-272A-0234 requires both the primary and the reserve areas to be sized at least 100 percent of the approved loading rates, and the local health officer may require the reserve sized using a stricter loading rate.

In practice this is the part of the property you cannot later build a shop, pool or extension over — and it is the most common reason a lot that looks big enough turns out not to be. Establish where it will sit before you finalize where the house goes, not after.

Permits expire

An approved permit is not indefinite. Benton-Franklin charges $325 to renew and requires it 30 days before expiry. Grays Harbor charges $310 per year for extensions. Others publish revision and re-review fees — Spokane $360 for a plan resubmittal beyond the one included, Benton-Franklin $250, Grays Harbor $238.

⚠️ Put the expiry date in your calendar the day your permit is issued. Renewal is cheap; letting it lapse and reapplying is not.

Repairs are often cheaper to permit than new systems

If you are repairing rather than installing, several jurisdictions charge substantially less:

• Grays Harbor — a repair permit is half the base permit fee where the failure is verified and the work completed within six months. One of the more homeowner-friendly provisions we found anywhere in the state.
• Whitman — a simple repair is $250 against $1,000 for a new residential review.
• Asotin — repair or modification $450, tank repair or replacement $275.
• Benton-Franklin — repair or replacement $600, tank only $350.

🎯 The rule also works in your favor here: the local health officer must allow the least expensive repair or replacement that meets the rule’s requirements. If you are being steered toward a full replacement when a repair would comply, that provision is worth citing.

What we could not source

• Typical review timelines — no jurisdiction we checked publishes a target turnaround for plan review
• Which jurisdictions require winter observation and on what trigger — we can confirm four charge for it, but not the criteria
• Permit validity periods for most jurisdictions — only renewal fees are published, not the terms
• Whether jurisdictions accept homeowner-prepared designs at all; some clearly do, others are silent

This site is an independent information resource. We are not a health jurisdiction, a designer or an installer, and we are not affiliated with the Washington State Department of Health or any county health department. Your local health jurisdiction issues the permit and its process governs. Where this page and your jurisdiction disagree, your jurisdiction is right.

Sources

• WAC 246-272A-0230, design requirements and Table VI — rule text
• WAC 246-272A-0234, reserve area sizing — rule text
• WAC 246-272A-0340, approval of installers, pumpers and maintenance service providers — rule text
• Chapter 18.210 RCW, on-site wastewater treatment system designer licensing — statute
• Asotin County Health District, permit process and fees — PDF
• Spokane Regional Health District, 2026 fee schedule — PDF
• Thurston County PHSS, 2025 and 2024 fee schedules — PDF
• Tacoma-Pierce County Health Department, fee schedule — page
• Benton-Franklin Health District, OSS construction permit application — PDF
• Grays Harbor County, 2026 EH fee schedule — PDF
• Whitman County Public Health, permit fees — page
• Mason County, 2026 EH fee schedule — PDF
• Walla Walla County, EH fee ordinance — PDF

Last reviewed August 2026. Process names and fees vary between the 35 local health jurisdictions; the sequence does not.