Planet Detroit · Lead in Drinking Water

GLWA communities with lead levels over 12 ppb, 2018–2025

From 2018 to 2025, 33 Great Lakes Water Authority communities in southeast Michigan reported a lead 90th-percentile above 12 ppb at least once. In 2025, Michigan lowered its lead action threshold from 15 ppb to 12 ppb. GLWA communities exceeded 12 ppb during 76 sampling periods between 2018 and 2025. Toggle the views below to see how often each community surpassed that threshold and how high readings climbed.

About this map. Each community is a public water system that purchases finished drinking water from GLWA. Lead in tap water typically comes from lead service lines and household plumbing. GLWA is required to treat water to control corrosion to minimize the amount of lead that dissolves in drinking water. Michigan's lead and copper rule revisions lowered the action level from the federal 15 ppb to 12 ppb in 2025; readings shown are the 90th-percentile result of each compliance sampling round, with all rounds above 12 ppb between 2018 and 2025 included. One Hamtramck reading from 2018 used the older first-draw sampling protocol; all other readings used Michigan's stricter fifth-liter protocol.

Source: Michigan Department of Environment, Great Lakes, and Energy · Planet Detroit analysis