Sourced from the Asotin County On-Site Sewage System Code (official copy dated January 31, 2023), the Asotin County Health District 2024 OSS fee schedule, the district’s own program pages, and chapter 246-272A WAC — last checked August 2026. Where we could not source something, we say so.
Quick answer: Asotin County is one of only four Washington counties that already requires a septic inspection report when property changes hands — the statewide version of that rule does not arrive until February 1, 2027. The site evaluation here is $95, the cheapest published in the state, and a complete new residential permit package runs $785 with a licensed designer or $985 if you design it yourself. Resident homeowners may do their own routine inspections — but the report you hand a buyer must come from a licensed professional.
Selling here already means an inspection report — since before the state required it
Most of Washington is waiting for the statewide transfer-inspection rule to arrive on February 1, 2027. Asotin County wrote its own version into the county code years ago, and it is worth quoting in full because the exemptions matter as much as the rule:
“At the time of property transfer, except for intra-family transfers, judicial or nonjudicial foreclosures, probate proceedings, or other judicially ordered transfers, an OSS owner is required to provide to the property buyer a current operations and maintenance inspection report performed by an O&M professional, licensed under ACC 200.”
— Asotin County On-Site Sewage System Code, §160.B
Read it as a seller and four things stand out:
- It applies now. Not in 2027. If you are selling a home on septic in Asotin County this year, the buyer is entitled to a current report before closing.
- The exemptions are specific: transfers within a family, foreclosures of either kind, probate, and other court-ordered transfers. An ordinary sale is not exempt.
- “Current” ties back to the routine schedule — a report is current when it is within the inspection interval for your system type, below.
- The transfer report must come from a licensed O&M professional. This is the one inspection you cannot do yourself, and the distinction trips people up — more on that in a moment.
The practical consequence: when the statewide rule lands in 2027, almost nothing changes for Asotin County sellers. The county got there first.
How often your system must be inspected
From §160.A of the county code:
- Gravity systems, or pump-to-gravity systems — at least once every three years.
- Every other system type — annually, unless the manufacturer or the health officer requires more often.
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The inspection you can do yourself — and the one you cannot
Asotin’s code contains a distinction we have not seen drawn this cleanly anywhere else in the state. Under §200.E, routine inspections of an existing system may be performed by licensed O&M providers and resident homeowners. If you live in the house, you may inspect your own system on the routine schedule.
But the report required at property transfer under §160.B must be “performed by an O&M professional, licensed under ACC 200.” Those licenses are not casual: providers must pass a written examination, complete annual continuing education, and carry at least $100,000 in liability insurance.
So the homeowner path keeps your system legal year to year at no cost — and then the sale requires one professional report at the end. If you have been self-inspecting, do not let a closing date surprise you: book the professional inspection early, because “current” is measured against your system’s interval, not against the sale date.
What Asotin County charges
From the district’s 2024 fee schedule. Asotin prices the pieces separately, so the honest number is the package total.
| Component | Fee |
|---|---|
| Site and soil evaluation — 1 hour, up to 4 test pits included | $95 (then $95/hour beyond) |
| Application, plan review and final inspection | $240 |
| OSS permit — new residential, licensed designer and installer | $450 |
| OSS permit — new residential, homeowner design or install | $650 |
| OSS permit — replacement or reserve system | $500 |
| OSS permit — commercial | $600 |
| Modification, minor repair, or graywater | $450 |
| Tank repair or replacement | $275 |
| Complete package | Total |
|---|---|
| New residential, licensed ($95 + $240 + $450) | $785 |
| New residential, homeowner ($95 + $240 + $650) | $985 |
| Replacement/reserve | $740–$835 |
| Commercial | $935 |
Extra site visits during approval can draw the $95/hour surcharge, so a clean, complete application is worth real money.
Two comparisons worth making. First, the $95 site evaluation is the cheapest published in Washington — Kittitas charges $790 for the equivalent, eight times as much. Second, notice that homeowner design costs $200 more in permit fees here, not less ($650 against $450). That is the opposite of Benton-Franklin, where a homeowner design review is $150. Asotin prices in the extra staff time a homeowner design takes to shepherd through — which is fair warning about what the process will feel like.
Designing or installing it yourself: allowed, with strings
The code permits both, on terms that are specific enough to quote:
- Design: homeowners may design a system for their own residence only, with explicit written permission from the health district.
- Installation: a homeowner may install a system once every two years, after passing a district-administered competency test, following the approved design exactly, using no proprietary products (gravelless distribution excepted) — and they must intend to live in the home for at least two years after construction.
That last condition is the tell: the homeowner path exists for people building their own home, not for flippers. Between the $200 permit premium, the competency test and the residency condition, the county allows self-reliance while making sure it is not a shortcut.
Lot size, wells and the 200-foot sewer line
- Minimum lot size for a new system: 12,500 square feet. Smaller lots face a stack of extra conditions — more than 200 feet from public sewer, treatment level B at minimum, primary and reserve areas both proven, and an O&M contract.
- Within 200 feet of public sewer or a large on-site system, new septic systems are generally not allowed — you connect instead. The same rule pattern as Benton-Franklin and Chelan-Douglas, and it bites hardest when an old system fails near a sewer main.
- Wells: the standard setback from an individual well or spring is 100 feet; a reduction to 75 feet is possible but requires written designer justification under the WAC.
What we could not source
- The code’s formal adoption date. The official copy is dated January 31, 2023, and predates the April 2025 revision of the statewide WAC; local press has reported the district working on updates. Nothing above contradicts current state rules, but if a detail is decision-critical, confirm it is still the live text.
- An operational or annual permit fee. None appears on the schedule — consistent with the routine-inspection model rather than an annual-permit model, but we did not find it stated outright.
- What a licensed O&M professional charges for the transfer inspection itself. The private-market price is not published; the $95–$785 figures above are the district’s fees, not the inspector’s.
- How many on-site systems are in the county. Not published anywhere we could find.
The practical bits
| Asotin County Health District | 719 5th Street, Clarkston, WA 99403 |
| Phone | 509-243-3344 |
| Hours | Monday–Thursday, 7:30am–5:30pm |
One more local convenience worth knowing: the district’s provider list, dated April 13, 2026, covers installers and pumpers working in both Washington and Idaho — sensible for a county where the nearest city across the river is Lewiston.
Sources
- Asotin County On-Site Sewage System Code, official copy dated January 31, 2023 — PDF
- Asotin County Health District, 2024 OSS Fee Schedule — PDF
- Asotin County Health District — ac-hd.org
- WAC 246-272A-0270, on-site sewage system inspection at property transfer
- WAC 246-272A-0210(4), horizontal separations
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Frequently Asked Questions
Does Asotin County require a septic inspection when selling a house?
Yes — already, and it has for years. Under section 160.B of the county on-site sewage code, at property transfer the owner must give the buyer a current operations and maintenance inspection report performed by a licensed O&M professional. Intra-family transfers, foreclosures, probate and other court-ordered transfers are exempt. The statewide version of this rule does not start until February 1, 2027, so Asotin sellers are already ahead of it.
How much is a septic permit in Asotin County?
The complete package for a new residential system is $785 with a licensed designer and installer: a $95 site and soil evaluation, $240 for application, plan review and final inspection, and a $450 permit. Homeowner design or installation raises the permit to $650, making the package $985. A replacement or reserve system runs $740 to $835 all in, and tank repair or replacement alone is $275.
Can I inspect my own septic system in Asotin County?
For routine inspections, yes — the code allows resident homeowners to perform them, on the standard schedule of every three years for gravity and pump-to-gravity systems and annually for everything else. The one exception is the report required at property transfer, which must come from an O&M professional licensed under ACC 200.
Can a homeowner install their own septic system in Asotin County?
Yes, once every two years, with conditions: pass the district competency test, follow the approved design exactly, use no proprietary products (gravelless distribution excepted), and intend to live in the home for at least two years after construction. Homeowner design also needs explicit written permission and carries a $200 higher permit fee than a licensed design.