Septic pumping in Coles County, Illinois costs $300-$550 (avg $400). A new septic system installation costs $5,800-$11,600. USDA soil data rates 0% of county soils as suitable for septic absorption fields. Approximately 2,699 homes in this county use septic systems.
Septic System Costs in Coles County
| Service | Low | Average | High |
|---|---|---|---|
| Pumping / Cleaning | $300 | $400 | $550 |
| Routine Inspection | $200 | $300 | $400 |
| Real Estate Inspection | $400 | $550 | $750 |
| Minor Repair | $750 | $1,050 | $5,100 |
| Conventional Installation | $5,800 | $8,300 | $11,600 |
| Aerobic System Installation | $10,900 | $15,600 | $21,850 |
| Drainfield Replacement | $5,800 | $8,300 | $11,600 |
| Perc Test | $900 | $1,250 | $1,750 |
Cost estimates based on regional market data for Coles County, Illinois. Actual costs depend on system type, site conditions, and provider.
Soil & Septic Suitability in Coles County
Drainage Class
Well drained
Hydrologic Group
C
Unique Soil Types
57
Dominant Soil Types
| Soil Series | Coverage | Drainage | Hydro Group |
|---|---|---|---|
| Senachwine | 561 | Well drained | C |
| Martinsville | 285 | Well drained | B |
| Drummer | 216 | Poorly drained | B/D |
| Starks | 195 | Somewhat poorly drained | C/D |
| Dana | 192 | Moderately well drained | C |
Septic Tank Absorption Field Suitability
USDA NRCS rates soil suitability for septic absorption fields across this county:
Overall rating: Very limited
Septic Regulations & Permits in Coles County
State Regulatory Body
Illinois 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 Coles County health department for current permit requirements, fees, and approved system types.
Septic System FAQ for Coles County
How much does septic pumping cost in Coles County?
Septic pumping in Coles County, Illinois typically costs between $300 and $550, with an average of $400. 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 Coles County?
A conventional septic system installation in Coles County typically costs $5,800-$11,600. An aerobic treatment unit (ATU) costs $10,900-$21,850. Given the predominantly 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 Coles County?
Yes. Virtually all counties in Illinois 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 Coles County health department for current requirements and fees.
What soil types are in Coles County and how do they affect septic systems?
Coles County has predominantly Senachwine, Martinsville, Drummer soils. The dominant drainage class is Well drained with hydrologic group C. The USDA rates 0% of surveyed soils as "Not Limited" for septic absorption fields, 4.2% as "Somewhat Limited", and 95.8% as "Very Limited".
How often should I pump my septic tank in Coles 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 Illinois have mandatory pumping schedules — check with your local health department.
Can I install a conventional septic system in Coles County?
It depends on your specific site. USDA soil data shows that 95.8% of soils in Coles 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 ($900-$1750) and soil evaluation are required before the county will approve a system design.
How long does a septic system last in Coles County?
A well-maintained septic system in Coles 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 (Coles County has predominantly well drained soils). 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