Tap Water Quality Report
Tap water quality in ST. CHARLES, Missouri
Tap water in ST. CHARLES, Missouri receives a grade of C (70/100) from TapWaterSafety.org. It's served by ST CHARLES PWS. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Arsenic* significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in ST. CHARLES's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving ST. CHARLES.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 17.8 ppb, 296x above the EWG health guideline of 0.06 ppb.
Arsenic* significantly above health guideline
Moderate concernArsenic* detected at 0.736 ppb, 184x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 11.0 ppb, 110x above the EWG health guideline of 0.1 ppb.
EPA compliance record
Official U.S. EPA records for ST CHARLES PWS (system ID MO6010707) for the last 3 years. Checked 2026-10-07.
| Rule | Type | Since | Status |
|---|---|---|---|
| Lead and Copper Rule | Missed testing or reporting | 10/01/2024 | Open |
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Recommended filters for ST. CHARLES
Filters matched to the specific contaminants in ST. CHARLES's water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in ST. CHARLES's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
17.8 ppb | 0.06 | — | — | — | — | — | 296× over |
| Arsenic* Heavy metal |
0.736 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 184× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
11.0 ppb | 0.1 | 60.0 | 60 | — | — | — | 110× over |
| Bromochloroacetic acid* Disinfection byproduct |
2.03 ppb | 0.02 | — | — | — | — | — | 102× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
9.11 ppb | 0.15 | 80.0 | 100 | — | — | — | 61× over |
| Chromium (hexavalent) Heavy metal |
1.2 ppb | 0.02 | — | — | — | — | — | 60× over |
| Dichloroacetic acid Disinfection byproduct |
10.2 ppb | 0.2 | — | — | — | — | — | 51× over |
| Chloroform Disinfection byproduct |
7.65 ppb | 0.4 | — | — | — | — | — | 19× over |
| Bromodichloromethane Disinfection byproduct |
0.874 ppb | 0.06 | — | — | — | — | — | 15× over |
| Trichloroacetic acid Disinfection byproduct |
0.793 ppb | 0.1 | — | — | — | — | — | 7.9× over |
| Nitrate* Inorganic |
1.02 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 7.3× over |
| Atrazine* Pesticide/Herbicide |
0.2 ppb | 0.1 | 3.0 | 0.1 | 100 | 0.15 | — | Fails EU |
| Dibromoacetic acid Disinfection byproduct |
0.036 ppb | 0.03 | — | — | — | — | — | 1.2× over |
| Chlorate Disinfection byproduct |
190.0 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Dibromochloromethane Disinfection byproduct |
0.0551 ppb | 0.1 | — | — | — | — | — | Below guideline |
| Antimony* Heavy metal |
0.315 ppb | 1.0 | 6.0 | 10 | 20 | 1 | — | Below guideline |
| Barium Heavy metal |
99.3 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Nitrate and nitrite Inorganic |
0.0147 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | Below guideline |
| 1,4-Dioxane* Semi-volatile organic compound |
0.0288 ppb | 0.35 | — | — | 50 | 1 | — | Below guideline |
| Vanadium Other |
1.34 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Selenium* Heavy metal |
1.64 ppb | 30.0 | 50.0 | 20 | 40 | 30 | — | Below guideline |
| Monochloroacetic acid* Disinfection byproduct |
2.41 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
1.05 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
1.83 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monobromoacetic acid* Disinfection byproduct |
0.157 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Aluminum* Heavy metal |
2.15 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Strontium Radiological |
0.165 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Chromium (total)* Heavy metal |
1.38 ppb | — | 100.0 | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.466 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Lithium Other |
20.9 ppb | — | — | — | — | — | — | Below guideline |
| Nitrite* Inorganic |
0.0263 ppm | — | 1.0 | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from ST CHARLES PWS.