Drinking water quality · 2024
· Verified
What's in Madison, WI tap water
27 contaminants were measured in the Madison, WI water system's 2024 annual report. Each is shown below against its federal limit — 1 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 27
- Over federal limit
- 1
- Approaching the limit
- 0
- Worst contaminant
- Barium
- Service area
- WI
Where your water comes from · EPA SDWIS
Madison, WI's drinking water comes from ground water, drawn from 2 sources.
Source
- YP894
- YP889
Treatment
- YP894
- YP889
Distribution
Historical readings · EPA Six-Year Review (2012–2019)
18 historically-detected contaminants in Madison, WI
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
RADIUM 226 228 worst: 2014 | 4.08 pCi/L 82% near national p90 | 5 pCi/L | '14'17 |
NITRATE worst: 2015 | 4.7 mg/L within | 10 mg/L | '12'13'15'16'18'19 |
NITRATE NITRITE worst: 2014 | 4.5 mg/L within | 10 mg/L | '14'17 |
FLUORIDE worst: 2012 | 1.59 mg/L within | 4 mg/L | '12'13'14'15'16'17'18'19 |
GROSS ALPHA worst: 2014 | 3.18 pCi/L within | 15 pCi/L | '14 |
BARIUM worst: 2014 | 0.08 mg/L within below national p90 | 2 mg/L | '14'17 |
TTHM worst: 2016 | 0.00316 mg/L within | 0.08 mg/L | '13'14'15'16'17'18'19 |
CHROMIUM worst: 2014 | 0.0036 mg/L within below national p90 | 0.1 mg/L | '14'17 |
HAA5 worst: 2018 | 0.00183 mg/L within | 0.06 mg/L | '13'14'15'16'17'18'19 |
COPPER worst: 2012 | 0.39 mg/L below national p90 | — | '12'13'14'15'16'17'18'19 |
LEAD worst: 2012 | 0.0017 mg/L | — | '12'13'14'15'16'17'18'19 |
DBAA worst: 2013 | 0.00063 mg/L | — | '13'14'15'16'17'18 |
DCAA worst: 2016 | 0.00053 mg/L | — | '16'17'18 |
MBAA worst: 2017 | 0.00048 mg/L | — | '17'18 |
TCAA worst: 2018 | 0.00023 mg/L | — | '18 |
BROMODICHLOROMETHANE worst: 2014 | 0.0005 mg/L | — | '14'16 |
BROMOFORM worst: 2014 | 0.0008 mg/L | — | '14 |
DIBROMOCHLOROMETHANE worst: 2014 | 0.00099 mg/L | — | '14'15'16'17'19 |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ZincA naturally occurring metal that can also enter water from corroding pipes. | 3.8 ug/LAverageMedian Level Found | 5 ug/LMCL | Within the limit |
| ManganeseA naturally occurring metal from soil and rock. | 2.5 ug/LAverageMedian Level Found | 50 ug/LMCL | Within the limit |
| Chromium, TotalTotal chromium — the sum of all chromium forms, from natural deposits and industrial discharge. | Not detected ug/LAverageMedian Level Found | 100 ug/LMCLG | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
| IronA naturally occurring metal common in groundwater. | Not detected mg/LAverageMedian Level Found | 0.3 mg/LMCL | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
| NickelA metal from natural deposits and industrial discharge. | Not detected ug/LAverageMedian Level Found | 100 ug/LMCL | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
| SeleniumA trace element from natural deposits and industrial discharge. | Not detected ug/LAverageMedian Level Found | 50 ug/LMCLG | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0.4 ug/LAverageMedian Level Found | None set | Detected — no federal limit |
| SodiumA naturally occurring salt component. | 7.3 mg/LAverageMedian Level Found | None set | Detected — no federal limit |
| Strontium | 82 ug/LAverageMedian Level Found | None set | Detected — no federal limit |
PFAS ("forever chemicals")
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Perfluorohexanesulfonic acidPerfluorohexanesulfonic acid, a PFAS 'forever chemical.' | 6.6–7.3RangeSystem-wide | 10MCL | Within the limit |
| PFOAPerfluorooctanoic acid, a PFAS 'forever chemical' once used in nonstick and stain-resistant products. | Not detected ng/LAverageMedian Level Found | 4 ng/LMCL | Within the limit |
| PFOSPerfluorooctanesulfonic acid, a PFAS 'forever chemical' once used in firefighting foam and coatings. | Not detected ng/LAverageMedian Level Found | 4 ng/LMCL | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
| PFBAPerfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' | 36–47RangeSystem-wide | None set | Detected — no federal limit |
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Combined RadiumCombined radium-226 and radium-228 — naturally occurring radioactive elements. | 2.4 pCi/LAverageMedian Level Found | 5 pCi/LMCL | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
Inorganic chemicals
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| AtrazineA widely used agricultural herbicide that reaches water through runoff. | Not detected ug/LAverageMedian Level Found | 3 ug/LMCLG | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
| TetrachloroethyleneAn industrial solvent (PCE) used in dry cleaning and degreasing. | Not detected ug/LAverageMedian Level Found | 5 ug/LMCL | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
| TrichloroethyleneAn industrial solvent (TCE) used in metal degreasing. | Not detected ug/LAverageMedian Level Found | 5 ug/LMCL | Within the limit |
+By source (2)— Wells with Detections, Median Level Found
| |||
People also ask about Madison, WI's water
+Is Madison, WI tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Madison, WI water utility lists 1 contaminant at or above the federal limit: Barium. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in Madison, WI tap water?
27 contaminants were measured in Madison, WI's 2024 Consumer Confidence Report, spanning metals, inorganic chemicals, and pfas ("forever chemicals"). 23 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in Madison, WI tap water?
One contaminant in Madison, WI's 2024 report sits at or above the federal limit: Barium (10.5× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in Madison, WI tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is Barium, at 10.5× the federal threshold. It belongs to the metals family of contaminants.
+Where does the data on this page come from?
Every value is transcribed from Madison, WI'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 Madison, WI'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.