Water Quality Report · Updated October 07, 2026
MO AMERICAN ST LOUIS ST CHARLES COUNTIES
MO AMERICAN ST LOUIS ST CHARLES COUNTIES delivers tap water graded C (73/100) by TapWaterSafety.org. The utility serves approximately 1,111,000 residents in CHESTERFIELD, Missouri using surface water. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; Arsenic detected. For questions, the utility can be reached at 314-548-0199.
Is CHESTERFIELD tap water safe to drink?
MO AMERICAN ST LOUIS ST CHARLES COUNTIES delivers tap water that earns a grade of C (73/100) from TapWaterSafety.org — an average rating, with several contaminants above health guidelines but generally compliant with US legal limits.
The utility serves 1,111,000 residents in CHESTERFIELD, drawing from surface water. Despite being legal under US EPA standards, this water would fail the European Union's Drinking Water Directive, primarily due to haloacetic acids (haa9) significantly above health guideline.
Public testing data identifies 14 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Arsenic, Dichloroacetic acid, Chloroform, Chromium (hexavalent), Bromodichloromethane, Trichloroacetic acid, Dibromochloromethane, Dibromoacetic acid, Nitrate, Nitrate and nitrite, Atrazine. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
EPA compliance record
Official U.S. EPA records for MO AMERICAN ST LOUIS ST CHARLES COUNTIES (system ID MO6010716) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Quick actions for CHESTERFIELD residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for MO AMERICAN ST LOUIS ST CHARLES COUNTIES.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 22.8 ppb, 380x above the EWG health guideline of 0.06 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 20.7 ppb, 207x above the EWG health guideline of 0.1 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 30.9 ppb, 206x above the EWG health guideline of 0.15 ppb.
Arsenic detected
Moderate concernArsenic detected at 0.4 ppb.
Contact MO AMERICAN ST LOUIS ST CHARLES COUNTIES
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for CHESTERFIELD
Filters matched to the specific contaminants in this 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.
Score breakdown
This utility's overall score of 73/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). 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 |
22.8 ppb | 0.06 | — | — | — | — | — | 380× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
20.7 ppb | 0.1 | 60.0 | 60 | — | — | — | 207× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
30.9 ppb | 0.15 | 80.0 | 100 | — | — | — | 206× over |
| Arsenic Heavy metal |
0.4 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 100× over |
| Dichloroacetic acid Disinfection byproduct |
17.7 ppb | 0.2 | — | — | — | — | — | 89× over |
| Chloroform Disinfection byproduct |
26.2 ppb | 0.4 | — | — | — | — | — | 65× over |
| Chromium (hexavalent) Heavy metal |
1.26 ppb | 0.02 | — | — | — | — | — | 63× over |
| Bromodichloromethane Disinfection byproduct |
3.63 ppb | 0.06 | — | — | — | — | — | 61× over |
| Trichloroacetic acid Disinfection byproduct |
1.88 ppb | 0.1 | — | — | — | — | — | 19× over |
| Dibromochloromethane Disinfection byproduct |
0.992 ppb | 0.1 | — | — | — | — | — | 9.9× over |
| Dibromoacetic acid Disinfection byproduct |
0.275 ppb | 0.03 | — | — | — | — | — | 9.2× over |
| Nitrate Inorganic |
0.459 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 3.3× over |
| Nitrate and nitrite Inorganic |
0.469 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 3.3× over |
| Atrazine Pesticide/Herbicide |
0.133 ppb | 0.1 | 3.0 | 0.1 | 100 | 0.15 | — | Fails EU |
| Chlorate Disinfection byproduct |
163.4 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Vanadium Other |
2.09 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Bromoform Disinfection byproduct |
0.0399 ppb | 0.5 | — | — | — | — | — | Below guideline |
| 1,4-Dioxane Semi-volatile organic compound |
0.023 ppb | 0.35 | — | — | 50 | 1 | — | Below guideline |
| Molybdenum Other |
1.94 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.824 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Selenium Heavy metal |
0.267 ppb | 30.0 | 50.0 | 20 | 40 | 30 | — | Below guideline |
| Manganese Heavy metal |
0.179 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| 2,4-D Pesticide/Herbicide |
0.0333 ppb | 20.0 | 70.0 | — | — | — | — | Below guideline |
| Aluminum Heavy metal |
0.667 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Perfluorobutanoic Acid (PFBA) PFAS |
0.842 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.11 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| 2-Methoxyethanol Other |
0.383 ppb | — | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.639 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Lithium Other |
23.1 ppb | — | — | — | — | — | — | Below guideline |
| Nitrite Inorganic |
0.00667 ppm | — | 1.0 | — | — | — | — | Below guideline |
| Testosterone Other |
0.015 ppt | — | — | — | — | — | — | 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 (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
MO AMERICAN ST LOUIS ST CHARLES COUNTIES service area
This water system serves 1 community in St. Louis County, Missouri. Click any city for its dedicated tap water quality page.
Find the right filter for CHESTERFIELD water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.