Recent water testing in O Fallon, Missouri has returned PFAS readings above detection thresholds.

Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-05-14

PFAS in O Fallon Tap Water

PFAS has been detected in O Fallon, Missouri drinking water at a maximum level of 0.0093 ppt — below the EPA MCL of 4 ppt (PFOA/PFOS individually).

This analysis covers 139,544 residents across 2 ZIP codes in O Fallon.

O Fallon's overall water quality grade is C (69/100).

Is PFAS in O Fallon Water Safe?

PFAS was detected in O Fallon water but currently falls within EPA limits. However, some health organizations argue the EPA MCL may not be protective enough.

If you are concerned, a reverse osmosis or granular activated carbon filter can reduce pfas levels further.

PFAS Levels by ZIP Code

Average pfas level across O Fallon: 4 ppt

Health Effects of PFAS

• Increased risk of kidney and testicular cancer
• Thyroid disease and immune system suppression
• Reproductive problems and reduced fertility
• Elevated cholesterol and liver effects
• Developmental effects in infants and children

Health risk severity: High. Governed by the PFAS National Primary Drinking Water Regulation (2024).

How PFAS Gets Into Drinking Water

• Firefighting foam (AFFF) used at military bases and airports
• Industrial manufacturing (non-stick coatings, stain-resistant fabrics)
• Wastewater treatment plants that receive industrial discharge
• Landfill leachate from PFAS-containing consumer products

What to Do About PFAS in O Fallon Water

1. Install a reverse osmosis system (most effective — removes 90%+ of PFAS)
2. Granular activated carbon (GAC) filters remove some PFAS compounds
3. Look for NSF 53 or NSF 58 certification specifically tested for PFAS
4. Pitcher filters with activated carbon provide partial reduction

Look for filters certified under NSF 53 / NSF 58 for pfas removal.

Related

• PFAS — National Overview
• PFAS in Missouri
• Missouri Water Quality
• O Fallon Water Quality
• Check Your ZIP Code