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Tap water quality report

St. Louis, MO

EPA monitoring detected 25 contaminants across the 1 water supplier serving St. Louis. A detection doesn't automatically mean the water is unsafe — see the level at the main supplier for each below, with its EPA source and period.

1
water supplier
304,709
people served
25
contaminants found
Missouri rankings Lead in Missouri PFAS in Missouri

What was found in St. Louis's water

The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.

ContaminantLevel vs EPA limitSuppliersSource
Nitrate-Nitrite
4092 µg/L 41%
of the EPA limit 10000 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Nitrate
4067.5 µg/L 41%
of the EPA limit 10000 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Fluoride
650 µg/L 16%
of the EPA limit 4000 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Lithium
45.3 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2024
1/1 UCMR-5
Copper
43.6479 µg/L 3.4%
of the EPA limit 1300 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Nitrite
37.55 µg/L 3.8%
of the EPA limit 1000 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Total Haloacetic Acids (HAA5)
33.7 µg/L 56%
of the EPA limit 60 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Dichloroacetic Acid
28.65 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
TTHM
25.575 µg/L 32%
of the EPA limit 80 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Barium
25.3265 µg/L 1.3%
of the EPA limit 2000 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Chloroform
20.44 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Monochloroacetic Acid
6.6834 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Lead
6.0613 µg/L 40%
of the EPA limit 15 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Bromodichloromethane
4.996 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Monobromoacetic Acid
4.9795 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Trichloroacetic Acid
3.636 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Dibromoacetic Acid
2.8958 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Selenium
2.4296 µg/L 4.9%
of the EPA limit 50 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Chromium
1.735 µg/L 1.7%
of the EPA limit 100 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Dibromochloromethane
1.5565 µg/L
No EPA limit set
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Atrazine
1.315 µg/L 44%
of the EPA limit 3 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Simazine
1.0555 µg/L 26%
of the EPA limit 4 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Arsenic
1.05 µg/L 11%
of the EPA limit 10 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Antimony, Total
0.3840 µg/L 6.4%
of the EPA limit 6 µg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2019
1/1 SYR4
Lead
0.0018 mg/L 12%
of the EPA limit 0.0150 mg/L
Main supplier: ST LOUIS CITY PWS · 304,709 people · 2025
1/1 LCR
Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of the system's samples — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving St. Louis

SupplierPopulation served
ST LOUIS CITY PWS 304,709

Frequently asked questions about St. Louis tap water

Is St. Louis tap water safe to drink?

EPA testing detected 25 contaminants in the water serving St. Louis. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve St. Louis?

1 public water supplier report drinking-water monitoring for St. Louis, Missouri to the EPA. Each is listed above with its population served.

What contaminants are in St. Louis's water?

The contaminants EPA monitoring detected in St. Louis include Nitrate-Nitrite, Nitrate, Fluoride, Lithium, Copper. The full list, with the level at the main supplier and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.