Looking for a drain field contractor in St. Mary, MO? Describe your project once and up to three licensed septic installers who work in St. Mary and Ste. Genevieve County get back to you with a quote. It's free and there is no obligation.
St. Mary is home to about 306 people (2024 Census Bureau estimate), a stable community (−0.6% since 2020). With 511 people per sq mi, it is a semi-rural area. Aging septic systems on rural and suburban lots eventually need new drain fields.
St. Mary at a glance
- Population (Census Bureau estimate, 2024)
- 306 (−0.6% since 2020)
- Rank in Missouri
- 565th of 938 cities and towns
- Land area
- 0.6 sq mi
- Population density
- 511 people per sq mi (semi-rural)
- Type
- City (St. Mary city)
- Main county
- Ste. Genevieve County
What to check before hiring in St. Mary
- Permit: in Missouri, drain field work is permitted by the state or county health department.
- Soil test: a new soil evaluation may be required to size the field.
- Alternatives: poor soils may call for a mound or an advanced treatment unit.
- Price drivers: soil, system type, lot access and landscaping restoration.
Useful official resources
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EPA: septic systems
Official information and guidance.
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EPA: types of septic systems
Official information and guidance.
Services available in St. Mary
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Drain field replacement
Design, permit and installation of a new drain field, conventional or alternative.
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Drain field diagnosis and repair
Diagnosis of a failing field and repairs such as line jetting or distribution box replacement.
Frequently asked questions in St. Mary
How much does drain field replacement cost in St. Mary, MO?
It depends on the soil, the system type and access. Describe your problem: installers who serve St. Mary reply with a quote.
How long does it take?
Design and permit can take weeks; installation often takes a few days.
Can I use my plumbing meanwhile?
Limit water use; the installer may pump the tank to buy time.
Which licensed septic installers will contact me?
Up to three independent licensed septic installers who serve St. Mary and the surrounding area, chosen for the service you need. Your details are shared only with your consent.
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.