Columbia County Septic Permit Costs and Plat Rules

Sourced from Columbia County Public Health’s land development and environmental health pages and its Master Application for On-Site Sewage Disposal Permit, revised September 2025, together with chapter 246-272A WAC — last checked August 2026. Where we could not source something, we say so.

What it costs

These come from the county’s Master Application for On-Site Sewage Disposal Permit, revised September 2025.

The bundling is the thing to notice. In most Washington counties the site evaluation is a separate bill on top of the permit — $790 in Kittitas, $500 in Klickitat, $335 in Skamania. Columbia folds it into a single $395 payment.

For comparison, a straightforward new residential system costs roughly $395 here, against $530 in Skamania, $1,000 in Klickitat, $1,100 in Walla Walla and $1,705 in Kittitas. Columbia is a small county and its fee structure reflects that, but the gap is real and worth knowing if you are choosing where to build in south-east Washington.

The inspection rule that is not about selling

Columbia is in an unusual position in our Washington matrix. It does not require an inspection to sell a house. It does require one for certain land development steps, and the county states it directly:

“Rural Housing Certificate or Short Plat: A licensed evaluator must assess the current system’s functionality. Failing systems must be repaired before further development.”

Two consequences follow, and both are easy to walk into:

• Dividing land triggers an evaluation of the existing system, even though selling the house on it would not.
• A failure discovered at that point stops the project. Not delays it — the county’s wording is that failing systems must be repaired before further development.

There is a parallel rule for expansions. Adding to a home requires verifying that the existing system can handle the increased capacity, and any modification has to be reviewed and approved by Columbia County Public Health. If the parcel has no existing system at all, a site evaluation determines both whether a septic system is feasible and what the minimum lot size will be.

The wider Land Development Review

For permits and certificates submitted to the county’s Building and Planning Division, Public Health may require a Land Development Review. Four things get assessed:

The county asks you to have site plans, soil reports and water quality test results ready when you apply, rather than gathering them once the file is open.

If you are on a well, the water test comes first

This catches people, because it is a health department requirement sitting in front of a septic permit. Columbia County Public Health requires water testing for nitrate and total coliform, from an accredited lab, and the results must be submitted to their office before any permits are issued. The results have to confirm the water is safe to drink.

Two more well points worth having in advance:

• A Notice of Intent must go to the Department of Ecology 72 hours before drilling. The county is explicit that an NOI is not a permit — withdrawal is only legal once confirmed.
• You may need a water right if you plan to use more than 5,000 gallons per day or irrigate more than half an acre.

You can install it yourself

The application offers a straightforward choice for who installs the system: property owner or licensed installer. Columbia has not closed the homeowner route the way Chelan-Douglas and Walla Walla have.

Per the application, a permit is valid for five years from the first approval date, and an owner-installed system requires at least two inspections before final approval. The county separately licenses sewage disposal system installers and septic tank pumpers, each with its own application form.

The appeal path is printed on the application and matches the pattern used elsewhere in the state: if an application is denied you may request a hearing before the Health Officer in writing within 30 days of the notice of denial, and the hearing must be set within 30 days of that request.

If you are selling in Columbia County

We found no local rule requiring a septic inspection to sell a house in Columbia County, and no mention anywhere of the statewide change under WAC 246-272A-0270 that takes effect on February 1, 2027.

That said, Columbia is better placed than most for the transition. It already requires a licensed evaluator to assess an existing system for a Rural Housing Certificate or Short Plat, which means the county already works with licensed evaluators and already has a process for receiving their assessments. The 2027 change extends that to ordinary sales rather than introducing something the county has never done.

What we could not source

• Any county statement about the February 1, 2027 statewide transfer inspection. Nothing on the pages we checked.
• A published list of licensed evaluators, installers or pumpers. The county licenses installers and pumpers and publishes the application forms, but we did not find a roster of who currently holds those licenses.
• The minimum lot sizes. The county says site restrictions and minimum lot size are assessed during review, but does not publish the thresholds.
• Test hole specifications. Number, depth and dimensions are not published on the pages or the master application.
• What “Multiple Lots $175 and $100” covers exactly — presumably a first lot and each additional, but the form does not spell it out. Ask before applying.
• How many on-site systems are in the county. Not published anywhere we could find.

The practical bits

Sources

• Columbia County Public Health, Land Development — columbiacopublichealth.org
• Columbia County Public Health, Master Application for On-Site Sewage Disposal Permit, revised September 2025
• Washington State Department of Ecology, well construction and water rights guidance
• WAC 246-272A; WAC 246-272A-0270, inspection at property transfer from February 1, 2027