Septic pumping in St. Mary Parish, Louisiana costs $250-$500 (avg $350). A new septic system installation costs $5,050-$10,100. USDA soil data rates 0% of county soils as suitable for septic absorption fields. Approximately 5,692 homes in this county use septic systems.
Septic System Costs in St. Mary Parish
| Service | Low | Average | High |
|---|---|---|---|
| Pumping / Cleaning | $250 | $350 | $500 |
| Routine Inspection | $200 | $250 | $350 |
| Real Estate Inspection | $350 | $500 | $700 |
| Minor Repair | $650 | $900 | $4,400 |
| Conventional Installation | $5,050 | $7,200 | $10,100 |
| Aerobic System Installation | $9,450 | $13,500 | $18,900 |
| Drainfield Replacement | $5,050 | $7,200 | $10,100 |
| Perc Test | $750 | $1,100 | $1,550 |
Cost estimates based on regional market data for St. Mary Parish, Louisiana. Actual costs depend on system type, site conditions, and provider.
Soil & Septic Suitability in St. Mary Parish
Drainage Class
Very poorly drained
Hydrologic Group
D
Unique Soil Types
36
Dominant Soil Types
| Soil Series | Coverage | Drainage | Hydro Group |
|---|---|---|---|
| Schriever | 224 | Poorly drained | D |
| Iberia | 197 | Poorly drained | D |
| Aquents | 173 | Very poorly drained | D |
| Dupuy | 172 | Somewhat poorly drained | C |
| Allemands | 151 | Very poorly drained | A/D |
Septic Tank Absorption Field Suitability
USDA NRCS rates soil suitability for septic absorption fields across this county:
Overall rating: Very limited
Groundwater & Water Table in St. Mary Parish
Monitoring Wells
3
Avg Depth to Water
7.5 ft
Median Depth
7.6 ft
Shallowest Recorded
3.5 ft Shallow Risk
Moderate water table depth. Some sites may require modified systems or mound systems.
Source: USGS National Water Information System. Based on 99 measurements from monitoring wells.
Septic Regulations & Permits in St. Mary Parish
State Regulatory Body
Louisiana 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 St. Mary Parish health department for current permit requirements, fees, and approved system types.
Septic System FAQ for St. Mary Parish
How much does septic pumping cost in St. Mary Parish?
Septic pumping in St. Mary Parish, Louisiana typically costs between $250 and $500, with an average of $350. 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 St. Mary Parish?
A conventional septic system installation in St. Mary Parish typically costs $5,050-$10,100. An aerobic treatment unit (ATU) costs $9,450-$18,900. Given the predominantly very poorly 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 St. Mary Parish?
Yes. Virtually all counties in Louisiana 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 St. Mary Parish health department for current requirements and fees.
What soil types are in St. Mary Parish and how do they affect septic systems?
St. Mary Parish has predominantly Schriever, Iberia, Aquents soils. The dominant drainage class is Very poorly 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 St. Mary Parish?
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 5,692 septic systems in St. Mary Parish, there are many local providers offering regular pumping services.
Does the water table in St. Mary Parish affect septic systems?
Yes. The average groundwater depth in St. Mary Parish is approximately 7.5 feet, based on USGS monitoring data from 3 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.
Can I install a conventional septic system in St. Mary Parish?
It depends on your specific site. USDA soil data shows that 100% of soils in St. Mary Parish 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 ($750-$1550) and soil evaluation are required before the county will approve a system design.
How long does a septic system last in St. Mary Parish?
A well-maintained septic system in St. Mary Parish 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 (St. Mary Parish has predominantly very poorly 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