Drinking water quality · 2024
· Verified
What's in St Louis, MO tap water
19 contaminants were measured in the St Louis, MO water system's 2024 annual report. Each is shown below against its federal limit.
- Reporting year
- 2024
- Contaminants measured
- 19
- Over federal limit
- 0
- Approaching the limit
- 1
- Service area
- MO
Where your water comes from · EPA SDWIS
St Louis, MO's drinking water comes from surface water, drawn from 4 sources.
Source
- MISSISSIPPI RIVER · 2
- MISSOURI RIVER · 2
Treatment
- CHAIN OF ROCKS
- HOWARD BEND
Distribution
Compliance history
Federal Safe Drinking Water Act violation & enforcement records (EPA SDWIS). A violation is a regulatory determination by the state or EPA — separate from the measured levels above.
- Monitoring & reporting1 violation on record · most recent Dec 20251 open
Source: EPA SDWIS / ECHO. View the full federal record on EPA ECHO ↗
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChloramineA longer-lasting disinfectant made by combining chlorine with ammonia. | 3.66 mg/LHighest single sampleSystem-wide | 4 mg/LMCL | Approaching the limit |
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| HAA5Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. | 36 ug/LMaximumSystem-wide | None set | Within the limit |
| TTHMTotal trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. | 18.2 ug/LRunning annual avgDistribution | None set | Within the limit |
Other
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Nitrate Nitrite | 2.099 mg/LMaximumSystem-wide | 10 mg/LMCL | Within the limit |
| Chromium | 0.93 ug/LMaximumSystem-wide | None set | Within the limit |
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| FluorideA mineral often added to drinking water to help prevent tooth decay. | 0.76 mg/LMaximumSystem-wide | 4 mg/LMCL | Within the limit |
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| AtrazineA widely used agricultural herbicide that reaches water through runoff. | 0.57 ug/LMaximumSystem-wide | None set | Within the limit |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| LeadA toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. | 2.12 ug/L90th percentileAt the tap | None set | Within the limit |
| Antimony | 0.31 ug/LMaximumSystem-wide | None set | Within the limit |
| ArsenicA naturally occurring element that also enters water from industry and agriculture. | 0.39 ug/LMaximumSystem-wide | None set | Within the limit |
| SeleniumA trace element from natural deposits and industrial discharge. | 1.18 ug/LMaximumSystem-wide | None set | Within the limit |
| CopperA metal that enters water from corroding household plumbing. | 0.0176 mg/L90th percentileAt the tap | 1.3 mg/LAction level | Within the limit |
| BariumA metal from erosion of natural deposits and industrial discharge. | 0.027 mg/LMaximumSystem-wide | 2 mg/LMCL | Within the limit |
| LithiumA naturally occurring element found in some groundwater. | 27.5 ug/LAverageSystem-wide | None set | Detected — no federal limit |
| NickelA metal from natural deposits and industrial discharge. | 0.85 ug/LMaximumSystem-wide | None set | Detected — no federal limit |
Physical & aggregate
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | Not detected pCi/LMaximumSystem-wide | 15 pCi/LMCL | None detected |
| UraniumA naturally occurring radioactive metal from erosion of natural deposits. | Not detected ug/LMaximumSystem-wide | 30 ug/LMCL | None detected |
People also ask about St Louis, MO's water
+Is St Louis, MO tap water safe to drink in 2024?
Every one of the 19 contaminants measured in St Louis, MO's 2024 Consumer Confidence Report is below its federal limit. "Safe" under the EPA's drinking-water standards is health-based, not aesthetic — but by those standards, no measured contaminant in this report exceeds its enforceable threshold. Individual health concerns (e.g. immunocompromised, infant, pregnancy) may warrant additional filtering regardless of compliance.
+What contaminants are in St Louis, MO tap water?
19 contaminants were measured in St Louis, MO's 2024 Consumer Confidence Report, spanning metals, disinfection byproducts, and other. 7 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Are any contaminants in St Louis, MO tap water approaching the federal limit?
One contaminant is between 80% and 100% of the federal limit in this report: Chloramine. Approaching means measured but not in violation — a margin that can close quickly if conditions change.
+Where does the data on this page come from?
Every value is transcribed from St Louis, MO's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is St Louis, MO's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2024 report; a new report will replace it once the utility publishes its next annual update.