Septic inspections in Thurston County
Get your system inspected for your county renewal, before a home sale, or when something isn't working right.
Thurston County runs an operations and maintenance program for on-site septic systems. Homeowners are responsible for having their systems inspected on the schedule the county sets, and the results go into the county's online septic records. Your renewal notice tells you when your system is due and what kind of inspection it needs.
Who can do the inspection
A Thurston County certified septic professional can inspect any system. Some homeowners with qualifying conventional gravity, pressure distribution, or mound systems can get certified to inspect their own. Starting in 2026, the county requires self-inspectors to also get a satisfactory report from a certified professional every nine years.
Complex systems, shared systems, and those with advanced treatment units often need professional inspections, and some need monitoring or sampling as well.
Inspections when you buy or sell
Thurston County has requirements for septic systems when a property changes hands. If you're buying a rural home or a house on the water, ask early about the septic inspection, since a failing system can change the deal. Sellers who get the inspection done early avoid last-minute surprises during closing. Check the county's time-of-transfer rules or ask your agent for the current requirements.
What an inspection covers
- Measuring the sludge and scum levels in the tank
- Checking the baffles or tees, lids, and risers
- Looking for signs of leaks, cracks, or water getting into the tank
- Checking pumps, floats, and alarms on pressure and mound systems
- Walking the drain field for surfacing effluent, soggy spots, or odors
- Submitting the report to the county's database
Tip: You can look up past septic reports for your property in the county's online records. This is especially useful when you're buying a home.
Where we connect you with help
Common questions
How do I know when my septic inspection is due?
Thurston County sends renewal notices for systems in its operations and maintenance program. The notice lists your due date and which inspection type applies.
Does an inspection include pumping?
Not necessarily. The inspection tells you whether the tank needs pumping. Many companies can do both on the same visit if it does.
Can I inspect my own septic system?
Some homeowners can after completing the county's certification, and only for certain system types and locations. Everyone else needs a certified septic professional.
Other septic services
Septic backing up or alarm going off?
Call now instead of sending a form. Backups are a same-day problem.