Winnebago County, Illinois: drinking water report. Winnebago County in northern Illinois includes Rockford and surrounding communities, with a population
Winnebago County in northern Illinois includes Rockford and surrounding communities, with a population of about 285,000. The county draws its water primarily from deep wells tapping the Cambrian-Ordovician aquifer system, supplemented by shallower sand and gravel wells. Rockford's water utility operates over 50 production wells across the city. Unlike surface-water-dependent systems, this deep groundwater is naturally cold and mineral-rich, but it also reflects whatever has seeped into the ground over decades of industrial and agricultural activity.
Rockford has a well-documented industrial contamination history. The Southeast Rockford Groundwater Contamination Superfund site, driven by trichloroethylene (TCE) from former industrial operations, has affected drinking water wells in the area since the 1980s. Cleanup is ongoing but incomplete. According to the Illinois EPA's 2024 monitoring data, TCE remains detectable at low levels in several production wells within the plume area.
The EPA's UCMR5 data also shows PFAS detections in the Rockford water system. The Greater Rockford Airport has used AFFF firefighting foam, and the Camp Grant industrial area adds another layer of legacy contamination. A 2023 IEPA report noted that five community water systems in the county had PFAS concentrations above Illinois's proposed notification levels.
Rockford's multiple contamination sources mean that monitoring data matters more here than in cleaner regions. The city has been proactive about testing, but well-by-well variation means your tap water depends on which production wells are feeding your part of the distribution system on any given day.
Check your water to see current results for your ZIP code. For TCE and PFAS, activated carbon filters certified to NSF 53 handle both, and reverse osmosis adds another layer of protection. Our water filter guide compares options for industrial contaminants. Pull your detailed report for trend data, and see our Illinois page for statewide patterns.