Septic Systems in Mercer County, MO

Regulations, costs, soil data & local providers

Pop. 3,538 ~40% on septic ~566 septic homes Moderately well drained soil

Septic pumping in Mercer County, Missouri costs $200-$400 (avg $300). A new septic system installation costs $4,550-$9,100. USDA soil data rates 0% of county soils as suitable for septic absorption fields. Approximately 566 homes in this county use septic systems.

Septic System Costs in Mercer County

ServiceLowAverageHigh
Pumping / Cleaning$200$300$400
Routine Inspection$200$250$350
Real Estate Inspection$300$450$650
Minor Repair$550$800$4,000
Conventional Installation$4,550$6,500$9,100
Aerobic System Installation$8,500$12,150$17,000
Drainfield Replacement$4,550$6,500$9,100
Perc Test$650$950$1,350

Cost estimates based on regional market data for Mercer County, Missouri. Actual costs depend on system type, site conditions, and provider.

Soil & Septic Suitability in Mercer County

Drainage Class
Moderately well drained
Hydrologic Group
D
Unique Soil Types
41
Avg Bedrock Depth
2.6 ft

Dominant Soil Types

Soil SeriesCoverageDrainageHydro Group
Gara 493 Well drained C
Shelby 458 Moderately well drained C
Adair 391 Moderately well drained D
Armstrong 310 Somewhat poorly drained D
Pering 290 Somewhat poorly drained D

Septic Tank Absorption Field Suitability

USDA NRCS rates soil suitability for septic absorption fields across this county:

Not Limited (Good)0%
Somewhat Limited0%
Very Limited100%

Overall rating: Very limited

Source: USDA NRCS Soil Survey Geographic Database (SSURGO)

Septic Regulations & Permits in Mercer County

State Regulatory Body
Missouri 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 Mercer County health department for current permit requirements, fees, and approved system types.

Septic System FAQ for Mercer County

How much does septic pumping cost in Mercer County?
Septic pumping in Mercer County, Missouri typically costs between $200 and $400, with an average of $300. 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 Mercer County?
A conventional septic system installation in Mercer County typically costs $4,550-$9,100. An aerobic treatment unit (ATU) costs $8,500-$17,000. Given the predominantly moderately well drained soils in this area, some sites may require alternative system types. Costs include the tank, drainfield, permits, and labor.
Do I need a permit for a septic system in Mercer County?
Yes. Virtually all counties in Missouri 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 Mercer County health department for current requirements and fees.
What soil types are in Mercer County and how do they affect septic systems?
Mercer County has predominantly Gara, Shelby, Adair soils. The dominant drainage class is Moderately well drained with hydrologic group D. The USDA rates 0% of surveyed soils as "Not Limited" for septic absorption fields, 0% as "Somewhat Limited", and 100% as "Very Limited".
How often should I pump my septic tank in Mercer 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 Missouri have mandatory pumping schedules — check with your local health department.
Can I install a conventional septic system in Mercer County?
It depends on your specific site. USDA soil data shows that 100% of soils in Mercer County are rated "Very Limited" for septic absorption fields, while only 0% are "Not Limited." This means many properties will require alternative systems such as mound systems, pressure distribution systems, or aerobic treatment units. A percolation test ($650-$1350) and soil evaluation are required before the county will approve a system design.
How long does a septic system last in Mercer County?
A well-maintained septic system in Mercer 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 (Mercer County has predominantly moderately well drained soils). Regular pumping every 3-5 years and avoiding excess water usage are the two most effective ways to extend system life.

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Quick Facts

Population3,538
Est. Septic Homes566
Avg Pumping Cost$300
Drainage ClassModerately well drained
Septic SuitabilityVery limited

Common Septic Services

Pumping: $200-$400
Inspection: $200-$350
Repair: $550-$4,000
Installation: $4,550-$9,100

Data last updated: 2026-04-13