What a septic inspection costs in Washington
Nobody around here publishes prices, so here they are. A full septic inspection typically runs $300 to $600. Island County, which handles Camano, publishes its own $100 to $500 range for time-of-sale inspections. If you are selling in Snohomish County there are two more line items stacked on top, and we will walk the whole bill below.
The honest number, and what moves it
Three things push an inspection toward the top or bottom of the $300 to $600 range:
- System type. A gravity system is a tank, some pipe, and a drainfield; it inspects quickly. A pressure, ATU, or other alternative system adds a pump, floats, an alarm, and sometimes a treatment unit, and every one of those components gets checked.
- Access. Lids at grade under risers mean the inspector opens up and gets to work. Lids buried under two feet of lawn mean locating and digging, and that time is on the bill.
- Records. If the as-built drawing is on file with the county, the inspector knows where everything is before the truck leaves the shop. If it is missing, the system has to be found and mapped, which takes longer. Plenty of older systems around Cedarhome and East Stanwood have thin or missing records.
Selling in Snohomish County: the whole bill
Starting November 1, 2026, every septic property sale in Snohomish County requires an inspection by a Health District-certified septic professional plus a Report of Property Transfer (RPT) filed with the county. Here is the realistic total, line by line:
| Line item | Cost | Notes |
|---|---|---|
| Septic inspection | $300 to $600 | System type, access, and records move it |
| County RPT fee | $245 | Fixed county fee for 2026-27 |
| Pumping, if recommended | $400 to $700 | Only if the inspector calls for it |
| Realistic all-in | $545 to $1,545 | Bottom end if no pumping is needed |
The seller is responsible for getting this done, though like anything in a real estate deal it can be negotiated. The step-by-step seller process, exemptions, and the paperwork itself are covered on our point-of-sale inspection page.
Order at listing, not at mutual acceptance
Here is the timing trap. After the inspection, the county's Report of Property Transfer review takes up to 10 business days. Order the inspection when an offer comes in and those two weeks land right in the middle of your closing timeline, with your buyer watching the calendar.
Order it when you list instead. An accepted RPT is valid for 12 months, so the paperwork just waits, done, for whichever buyer shows up. If the inspection turns up a problem, you find out while you still have time to fix it on your schedule instead of renegotiating under deadline. Same money either way; ordering early just buys you the calendar.
What the inspection covers
You are paying for a full picture of the system, not a glance in the tank. A proper inspection checks:
- The tank: structural condition, watertightness, and lids.
- The baffles: the inlet and outlet fittings that keep solids out of the drainfield. A failed outlet baffle is one of the cheapest finds that prevents one of the most expensive failures.
- Sludge and scum levels: measured, not eyeballed. This is what decides whether pumping gets recommended.
- The drainfield: surface condition, signs of surfacing effluent or saturation, and how the field is taking water.
- System-specific components: on pressure and ATU systems, the pump, floats, alarm, and treatment components each get checked.
Camano Island is a different county with older rules
Camano Island sits in Island County, and Island County has required a time-of-sale septic inspection since 2008. This is not a new rule on the island; it has been part of every Camano sale for years. The inspection must be done by an Island County Licensed Maintenance Service Provider, it stays valid for 12 months for alternative systems and 3 years for conventional systems, and the county publishes a $100 to $500 cost range. And the rest of the state is catching up to both counties: under WAC 246-272A-0270, transfer inspections become mandatory in every Washington county on February 1, 2027. If your sale is on Camano, our Camano Island septic inspection page covers the process end to end.
Get an inspection quote with the real numbers
One call handles it: inspection, pumping if it's needed, and the county paperwork done right the first time.
Call (360) 454-9079Common questions
How much does a septic inspection cost in Washington?
Most full septic inspections run $300 to $600. Island County publishes a $100 to $500 range for its time-of-sale inspections. The price moves with system type (a gravity system is quicker to inspect than a pressure or ATU system), how hard the tank is to access, and whether the as-built records are on file or the inspector has to locate everything from scratch.
What does a septic inspection cost all-in when selling in Snohomish County?
Plan on $545 to $1,545 total: $300 to $600 for the inspection itself, the $245 county Report of Property Transfer fee, and $400 to $700 for pumping if the inspector recommends it. If the tank was pumped recently and levels look good, pumping may not be needed and the total stays near the bottom of that range.
What is the $245 Report of Property Transfer fee?
It is the fee Snohomish County charges to review and file the Report of Property Transfer, the paperwork that documents the septic inspection for a home sale under ordinance BOH26-02. The fee is $245 for 2026-27, the county's review takes up to 10 business days, and an accepted RPT is valid for 12 months.
What does the inspector actually check?
The tank and its structural condition, the inlet and outlet baffles, the sludge and scum levels, the condition of the drainfield, and the components specific to your system type, like the pump, floats, and alarm on a pressure system. The inspector also confirms the system matches the as-built record on file with the county.
When should I order the inspection if I am selling?
When you list the home, not when you get an offer. In Snohomish County the Report of Property Transfer review takes up to 10 business days after the inspection, and an accepted RPT is valid for 12 months. Ordering at listing means the paperwork is done sitting in a drawer before a buyer ever shows up, instead of holding your closing hostage.
Is the inspection requirement new on Camano Island too?
No. Camano Island is Island County, and Island County has required a time-of-sale septic inspection since 2008. The inspection must be done by an Island County Licensed Maintenance Service Provider, and it stays valid for 12 months for alternative systems and 3 years for conventional systems. Island County publishes a $100 to $500 cost range for these inspections.