O' Fallon Wastewater Treatment Plant
O'Fallon, MO · St. Charles County · Publicly Owned Treatment Works
- Average flow
- 6.7 MGD
- Design flow
- —
- NPDES permit
- MO0028720
- Effective
- Permit expires
- March 2025
- Population served
- 88,132
- CWNS 2022
O' Fallon Wastewater Treatment Plant is a publicly owned wastewater treatment works in O'Fallon, St. Charles County, Missouri treating an average of 6.7 million gallons per day, serving about 88,132 residents. Treatment on site includes clarifiers, uncovered lagoons, biogas balloons, biological treatment, other, biosolids aerobic digestion and other unit processes. It discharges under NPDES permit MO0028720 (effective), which expires in March 2025, with 0 recorded violations in the last three years. Planned upgrades on record: biosolids mechanical dewatering.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Clarifiers
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Uncovered lagoons
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Biogas balloons
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Biological Treatment, Other
unit processBiosolids Aerobic Digestion
unit processBiosolids Thickening
unit processDisinfection, UV
unit processFlow Equalization
unit processScreening
unit processBiosolids Mechanical Dewatering
planned upgradeUnlock exact unit counts →
Compliance snapshot (last 3 years)
- Total violations
- 0
- Effluent violations
- 0
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
2 verified contacts for O' Fallon Wastewater Treatment Plant, with validated emails and direct phone numbers.
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Names, validated emails and direct phone numbers for decision-makers at O' Fallon Wastewater Treatment Plant, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Missouri
O'Fallon · 4 mi away
0.1 MGD
Saint Peters · 5 mi away
4.83 MGD
Old Monroe · 7 mi away
—
Old Monroe · 7 mi away
0.05 MGD
Wentzville · 9 mi away
4.34 MGD
St. Charles · 10 mi away
0.0094 MGD
St. Charles · 10 mi away
—
Wentzville · 10 mi away
0.51 MGD
O' Fallon Wastewater Treatment Plant: frequently asked questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed September 11, 2026; facility record last updated April 24, 2025.