Water Quality: Madison, WI
17 water systems • 285,795 people served
Multiple Health ViolationsWater Quality Summary
Madison is served by 17 public water systems with a combined service population of 285,795 people, and has 247 EPA Safe Drinking Water Act violations on record. Critically, 26 of those are health-based violations, meaning one or more contaminants were detected above EPA-established safe levels — a serious public health concern. Madison's violation count is 654% above the national average for Wisconsin. Contaminants associated with violations include Disinfection Byproducts, E. coli, Stage 2 DBP, Total Organic Carbon.
Contaminants Found
Broad category of chemicals formed during disinfection, associated with increased cancer risk and adverse reproductive effects.
Common source: Reaction of disinfectants (chlorine, ozone, chloramines) with organic matter
Causes gastrointestinal illness; certain strains (e.g., O157:H7) can cause severe kidney failure and death.
Common source: Fecal contamination from humans or animals entering the water supply
EPA limit: Zero (no E. coli permitted in drinking water)
Trihalomethanes and haloacetic acids that increase cancer risk and may cause adverse reproductive outcomes.
Common source: Chlorine disinfection reacting with natural organic matter in source water
EPA limit: TTHM: 0.080 mg/L; HAA5: 0.060 mg/L
Not a direct health risk but reacts with disinfectants to form carcinogenic byproducts such as trihalomethanes.
Common source: Decaying plant material, algae, soil organic matter in source water
EPA limit: Treatment technique (must reduce TOC based on source water level)
Water Systems Serving Madison
| System Name | PWSID | Source | Population | Violations |
|---|---|---|---|---|
| MADISON WATER UTILITY | WI1130224 | Groundwater | 272,000 | 4 |
| WAUPUN CORRECTIONAL INST | WI1140142 | Groundwater | 3,706 | 21 |
| MENDOTA MENTAL HEALTH INST | WI1130235 | Groundwater | 2,787 | 6 |
| FOX LAKE CORRECTIONAL INSTITUTION | WI1140144 | Groundwater | 1,850 | 16 |
| SHOREWOOD HILLS WATERWORKS | WI1130236 | Groundwater | 1,670 | 19 |
| KETTLE MORAINE CORRECTIONAL INSTITUTION | WI4600449 | Groundwater | 1,544 | 1 |
| MAPLE BLUFF WATERWORKS | WI1130234 | Groundwater | 1,342 | 8 |
| LAKE FOREST WATER COOP | WI1130232 | Groundwater | 400 | 60 |
| APPLEWOOD HILL | WI1130244 | Groundwater | 125 | 7 |
| GORDON CORRECTIONAL CENTER | WI8160142 | Groundwater | 124 | 13 |
| DELAFIELD LAKES 402 | WI2686101 | Groundwater | 50 | 14 |
| WOODBRIDGE ESTATES | WI1133471 | Groundwater | 48 | 16 |
| PINE RIDGE APTS | WI1132627 | Groundwater | 45 | 8 |
| DELAFIELD WOODS 411 | WI2686336 | Groundwater | 28 | 8 |
| DELAFIELD WOODS 828 | WI2686337 | Groundwater | 26 | 5 |
| PIRATES COVE MOBILE HOME COMMUNITY | WI1540118 | Groundwater | 25 | 33 |
| DELAFIELD LAKES 404 | WI2686114 | Groundwater | 25 | 8 |
Concerned About Your Water?
A home water filter can remove common contaminants. NSF-certified filters are tested against EPA standards.
Consider a reverse osmosis system for comprehensive filtration or a carbon filter for basic improvement.
Other Cities in Wisconsin
Data Sources
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). Data includes all recorded violations for active community water systems.