Septic pumping in Lewis County, Washington costs $350-$700 (avg $500). A new septic system installation costs $7,300-$14,550. Approximately 6,572 homes in this county use septic systems.
Septic System Costs in Lewis County
| Service | Low | Average | High |
|---|---|---|---|
| Pumping / Cleaning | $350 | $500 | $700 |
| Routine Inspection | $300 | $400 | $550 |
| Real Estate Inspection | $500 | $700 | $1000 |
| Minor Repair | $900 | $1,300 | $6,350 |
| Conventional Installation | $7,300 | $10,400 | $14,550 |
| Aerobic System Installation | $13,650 | $19,500 | $27,300 |
| Drainfield Replacement | $7,300 | $10,400 | $14,550 |
| Perc Test | $1,100 | $1,550 | $2,150 |
Cost estimates based on regional market data for Lewis County, Washington. Actual costs depend on system type, site conditions, and provider.
Septic Regulations & Permits in Lewis County
State Regulatory Body
Washington State Department of Health
Inspection Required for Home Sale
Yes
Nitrogen Reduction Areas
Yes
Advanced Treatment Required
In designated areas
Mandatory time-of-sale inspection since 2008.
Contact the Lewis County health department for current permit requirements, fees, and approved system types.
Septic System FAQ for Lewis County
How much does septic pumping cost in Lewis County?
Septic pumping in Lewis County, Washington typically costs between $350 and $700, with an average of $500. Costs vary by tank size (1,000-1,500 gallons is typical), ease of access, distance from the pumping company, and how full the tank is. Most homeowners should pump their tank every 3-5 years.
How much does a new septic system cost in Lewis County?
A conventional septic system installation in Lewis County typically costs $7,300-$14,550. An aerobic treatment unit (ATU) costs $13,650-$27,300. Costs include the tank, drainfield, permits, and labor.
Do I need a permit for a septic system in Lewis County?
Yes. Virtually all counties in Washington require a permit before installing, repairing, or replacing a septic system. The permit process typically involves a soil evaluation or percolation test, system design by a licensed professional, application to the county health department, and one or more inspections during installation. Contact the Lewis County health department for current requirements and fees.
What soil types are in Lewis County and how do they affect septic systems?
Contact the county health department for soil evaluation requirements.
Is a septic inspection required when selling a home in Lewis County?
Yes. Washington requires a septic system inspection as part of the property transfer process. This typically involves a certified inspector evaluating the tank, drainfield, and all system components. The inspection cost in this area averages $700. If the system fails inspection, repairs or replacement may be required before the sale can proceed.
How often should I pump my septic tank in Lewis County?
The EPA recommends pumping your septic tank every 3-5 years for a typical household. The exact frequency depends on tank size, household size, and water usage. A 1,000-gallon tank serving a family of 4 should generally be pumped every 3 years. With approximately 6,572 septic systems in Lewis County, there are many local providers offering regular pumping services.
How long does a septic system last in Lewis County?
A well-maintained septic system in Lewis County typically lasts 25-30 years, though some components may need attention sooner. The concrete septic tank itself can last 40+ years, while the drainfield — the most critical and expensive component — usually lasts 15-25 years depending on soil conditions. Regular pumping every 3-5 years and avoiding excess water usage are the two most effective ways to extend system life.
Data last updated: 2026-04-13