Septic pumping in Lake County, Montana costs $300-$650 (avg $450). A new septic system installation costs $6,350-$12,750. Approximately 3,736 homes in this county use septic systems.
Septic System Costs in Lake County
| Service | Low | Average | High |
|---|---|---|---|
| Pumping / Cleaning | $300 | $450 | $650 |
| Routine Inspection | $250 | $350 | $500 |
| Real Estate Inspection | $450 | $650 | $900 |
| Minor Repair | $800 | $1,150 | $5,600 |
| Conventional Installation | $6,350 | $9,100 | $12,750 |
| Aerobic System Installation | $11,950 | $17,100 | $23,950 |
| Drainfield Replacement | $6,350 | $9,100 | $12,750 |
| Perc Test | $950 | $1,350 | $1,900 |
Cost estimates based on regional market data for Lake County, Montana. Actual costs depend on system type, site conditions, and provider.
Groundwater & Water Table in Lake County
Monitoring Wells
14
Avg Depth to Water
9.1 ft
Median Depth
7.7 ft
Shallowest Recorded
0.2 ft Shallow Risk
Moderate water table depth. Some sites may require modified systems or mound systems.
Source: USGS National Water Information System. Based on 440 measurements from monitoring wells.
Septic Regulations & Permits in Lake County
State Regulatory Body
Montana Department of Health/Environment
Inspection Required for Home Sale
No / Varies
Nitrogen Reduction Areas
No
Advanced Treatment Required
No
Contact county health department for specific requirements.
Contact the Lake County health department for current permit requirements, fees, and approved system types.
Septic System FAQ for Lake County
How much does septic pumping cost in Lake County?
Septic pumping in Lake County, Montana typically costs between $300 and $650, with an average of $450. 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 Lake County?
A conventional septic system installation in Lake County typically costs $6,350-$12,750. An aerobic treatment unit (ATU) costs $11,950-$23,950. Costs include the tank, drainfield, permits, and labor.
Do I need a permit for a septic system in Lake County?
Yes. Virtually all counties in Montana 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 Lake County health department for current requirements and fees.
What soil types are in Lake County and how do they affect septic systems?
Contact the county health department for soil evaluation requirements.
How often should I pump my septic tank in Lake 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. Some counties in Montana have mandatory pumping schedules — check with your local health department.
Does the water table in Lake County affect septic systems?
Yes. The average groundwater depth in Lake County is approximately 9.1 feet, based on USGS monitoring data from 14 wells. While this is sufficient for many conventional systems, sites with lower elevations or seasonal water table fluctuations may require alternative system designs. A site-specific evaluation is always recommended.
How long does a septic system last in Lake County?
A well-maintained septic system in Lake 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