Water Service Outages in Wisconsin by City

Wisconsin drinking water record

• Community water systems: 1,022 active systems serve about 4,236,576 people. 836 of them (82%) serve 3,300 people or fewer; 961 draw mainly on groundwater and 61 on surface water.
• Health-based violations since 2015: 1,042, at 388 systems (38% of all systems). That share is 36th of 50 states (1 = lowest).
• Most common problems: contaminant averages over the limit (481); uncorrected Ground Water Rule deficiencies (129); uncertified operators (91). Source: EPA SDWIS
• Largest system: Milwaukee Waterworks, about 626,000 people, with 0 health-based violations since 2015. Source: EPA SDWIS
• Housing age: the median Wisconsin home was built in 1975 (US 1980). Older housing stock means more lead service lines left to replace. Source: US Census Bureau, ACS 2020–2024 (table B25035)
• Storm damage to water service: NOAA storm narratives mention water mains, boil water notices or lost water service in 13 episodes in Wisconsin since 2015. Source: NOAA Storm Events Database
• January 1, 2020, Oconto (flood): “The high water mainly affected Pecor, McDonald, Water, Turner, Ontario, Bridge, First and Second streets.” Source: NOAA Storm Events Database
• December 30, 2019, Oconto (flood): “The high water mainly affected Pecor, McDonald, Water, Turner, Ontario, Bridge, First and Second streets.” Source: NOAA Storm Events Database

Checked September 2026.