What was found in Madison'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.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 3940 µg/L 39% of the EPA limit 10000 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019
Highest in the city: 4640 µg/L — MENDOTA MENTAL HEALTH INST · 2,787 people · 2019 | 7/11 | SYR4 |
| Nitrate-Nitrite | 4276.5 µg/L 43% of the EPA limit 10000 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 7/11 | SYR4 |
| Fluoride | 911 µg/L 23% of the EPA limit 4000 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019
Highest in the city: 1360 µg/L — MENDOTA MENTAL HEALTH INST · 2,787 people · 2019 | 4/11 | SYR4 |
| Copper | 189.3 µg/L 15% of the EPA limit 1300 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2018
Highest in the city: 1300 µg/L — MENDOTA MENTAL HEALTH INST · 2,787 people · 2019 | 11/11 | SYR4 |
| Barium | 56.64 µg/L 2.8% of the EPA limit 2000 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2018
Highest in the city: 73.1 µg/L — MENDOTA MENTAL HEALTH INST · 2,787 people · 2017 | 9/11 | SYR4 |
| Gross Alpha, Excl. Radon And U | 9.57 pCi/L 64% of the EPA limit 15 pCi/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019
Highest in the city: 12.9 pCi/L — WOODBRIDGE ESTATES · 48 people · 2015 | 9/11 | SYR4 |
| TTHM | 10.928 µg/L 14% of the EPA limit 80 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 4/11 | SYR4 |
| Gross Beta Particle Activity | 7.735 pCi/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 2/11 | SYR4 |
| Lead | 5.655 µg/L 38% of the EPA limit 15 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2018
Highest in the city: 7.71 µg/L — MENDOTA MENTAL HEALTH INST · 2,787 people · 2019 | 9/11 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 4.6 µg/L 77% of the EPA limit 6 µg/L Highest in the city: LAKE FOREST WATER COOP · 400 people · 2018 | 1/11 | SYR4 |
| Xylenes, Total | 4.3 µg/L 0% of the EPA limit 10000 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 1/11 | SYR4 |
| Combined Radium (-226 And -228) | 4.18 pCi/L 84% of the EPA limit 5 pCi/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 9/11 | SYR4 |
| Chloroform | 3.9 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 3/11 | SYR4 |
| Bromodichloromethane | 3.88 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 3/11 | SYR4 |
| Chromium | 2.902 µg/L 2.9% of the EPA limit 100 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2018
Highest in the city: 3.48 µg/L — MENDOTA MENTAL HEALTH INST · 2,787 people · 2017 | 2/11 | SYR4 |
| Tetrachloroethylene | 3.45 µg/L 69% of the EPA limit 5 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 1/11 | SYR4 |
| Total Haloacetic Acids (HAA5) | 3.316 µg/L 5.5% of the EPA limit 60 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 4/11 | SYR4 |
| Dibromochloromethane | 3.16 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019
Highest in the city: 3.2 µg/L — MAPLE BLUFF WATERWORKS · 1,342 people · 2019 | 4/11 | SYR4 |
| Carbon Tetrachloride | 2.5895 µg/L 52% of the EPA limit 5 µg/L Highest in the city: LAKE FOREST WATER COOP · 400 people · 2019 | 1/11 | SYR4 |
| Bromoform | 1.82 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 4/11 | SYR4 |
| Dichloroacetic Acid | 1.74 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 3/11 | SYR4 |
| Combined Uranium | 1.53 µg/L 5.1% of the EPA limit 30 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 5/11 | SYR4 |
| Dibromoacetic Acid | 1.33 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019
Highest in the city: 1.4 µg/L — MAPLE BLUFF WATERWORKS · 1,342 people · 2019 | 4/11 | SYR4 |
| Selenium | 1.02 µg/L 2% of the EPA limit 50 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2018 | 1/11 | SYR4 |
| Trichloroacetic Acid | 0.8120 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 2/11 | SYR4 |
| Arsenic | 0.7159 µg/L 7.2% of the EPA limit 10 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2018 | 1/11 | SYR4 |
| Toluene | 0.6985 µg/L 0.1% of the EPA limit 1000 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 1/11 | SYR4 |
| Ethylbenzene | 0.6800 µg/L 0.1% of the EPA limit 700 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 1/11 | SYR4 |
| Monobromoacetic Acid | 0.5690 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 2/11 | SYR4 |
| Trichloroethylene | 0.4800 µg/L 9.6% of the EPA limit 5 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 1/11 | SYR4 |
| cis-1,2-Dichloroethylene | 0.4000 µg/L 0.6% of the EPA limit 70 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 1/11 | SYR4 |
| Cadmium | 0.2932 µg/L 5.9% of the EPA limit 5 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2018 | 1/11 | SYR4 |
| Styrene | 0.1895 µg/L 0.2% of the EPA limit 100 µg/L Highest in the city: LAKE FOREST WATER COOP · 400 people · 2019 | 1/11 | SYR4 |
| 1,1,1-Trichloroethane | 0.1000 µg/L 0.1% of the EPA limit 200 µg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2019 | 1/11 | SYR4 |
| Pfba | 0.0465 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2024 | 1/11 | UCMR-5 |
| Lead | 0.0018 mg/L 12% of the EPA limit 0.0150 mg/L Main supplier: MADISON WATER UTILITY · 272,000 people · 2023
Highest in the city: 0.0081 mg/L — LAKE FOREST WATER COOP · 400 people · 2024 | 11/11 | LCR |
| PFHXS | 0.0073 µg/L No EPA limit set Main supplier: MADISON WATER UTILITY · 272,000 people · 2024 | 1/11 | UCMR-5 |
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 Madison
| Supplier | Population served |
|---|---|
| MADISON WATER UTILITY | 272,000 |
| MENDOTA MENTAL HEALTH INST | 2,787 |
| SHOREWOOD HILLS WATERWORKS | 1,670 |
| MAPLE BLUFF WATERWORKS | 1,342 |
| LAKE FOREST WATER COOP | 400 |
| APPLEWOOD HILL | 125 |
| LAKE POINTE APTS - WELL 1 5320-5326 | 60 |
| LAKE POINTE APTS - WELL 2 5312-5318 | 60 |
| LAKE POINTE/MARINA BAY | 50 |
| WOODBRIDGE ESTATES | 48 |
| PINE RIDGE APTS | 45 |
Frequently asked questions about Madison tap water
Is Madison tap water safe to drink?
EPA testing detected 37 contaminants in the water serving Madison. 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 Madison?
11 public water suppliers report drinking-water monitoring for Madison, Wisconsin to the EPA. Each is listed above with its population served.
What contaminants are in Madison's water?
The contaminants EPA monitoring detected in Madison include Nitrate, Nitrate-Nitrite, Fluoride, Copper, Barium. 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.