The Illinois EPA considers all surface-water sources susceptible to potential pollution and requires treatment of surface-water supplies. Highland Park identifies possible source-water influences including sediment, shoreline erosion, wet-weather sewer overflows, wastewater-treatment bypasses, stormwater runoff, and air deposition. The report states that the primary intake is far enough offshore that shoreline effects are not considered a factor in its water quality, while the secondary intakes may be influenced by potential nearshore sources.

Lead remains an important property-level consideration. Highland Park completed a service-line material inventory in 2024 and identified 1,805 residences with lead or galvanized service lines out of 10,449 water services. The City reports that replacement work is underway.

The report advises that lead in drinking water primarily comes from service lines and household plumbing materials. It recommends flushing stagnant water, considering a properly certified lead-reduction filter, and requesting testing when residents are concerned.

Highland Park also participated in UCMR 5 monitoring for lithium and 29 PFAS compounds. Samples were collected every three months between May 2024 and February 2025. According to the report, no lithium or PFAS compounds were detected in those samples.

The report further notes that immunocompromised people, some elderly adults, infants, and others with heightened vulnerability should seek advice from their healthcare providers about drinking water and microbial risks.

Northbrook’s 2025 Water Consumer Confidence Report states that the Village routinely tests for more than 120 contaminants and that the regulated substances detected in the reported monitoring were within applicable U.S. EPA and Illinois EPA standards. The report also states that none of the regulated substances summarized in its routine testing section exceeded applicable regulations. 

Lead monitoring requires additional context. Testing completed in 2025 produced a lead 90th-percentile result of 16 parts per billion, above the 15-parts-per-billion action level, with seven sampling sites above that action level. Copper’s 90th-percentile result was 0.24 parts per million, below its 1.3-parts-per-million action level, and no copper sites exceeded the action level. The report’s table lists no lead or copper violation, but Northbrook separately posted a public notice concerning the July 2025 lead action-level exceedance. An action-level exceedance triggers follow-up requirements and is not the same as a contaminant exceeding an MCL.

Beginning in 2025, Northbrook was required to sample every six months and test 60 sites with lead service lines. The Village reports that it completed and updated its service-line inventory, submitted it to Illinois EPA in April 2026, and maintains a cost-sharing replacement program. Northbrook also requires complete lead-line replacement at properties undergoing substantial remodeling or demolition.

Northbrook states that Lake Michigan source water and water leaving its treatment plant are effectively free of lead. When lead is found at a tap, the Village identifies service lines, household plumbing, solder, faucets, valves, and fittings as the typical potential sources. The Village adds poly-orthophosphate to reduce corrosion and lead leaching.

Northbrook uses chlorine to disinfect its municipal water. The reported chlorine level ranged from 1.0 to 1.5 milligrams per liter, with a reported value of 1.2 milligrams per liter. Chlorine is an essential part of municipal disinfection, though individual customers may perceive its taste or odor differently.

Turbidity measures water cloudiness and is also used to evaluate filtration effectiveness. Northbrook reported a highest single turbidity result of 0.05 NTU, compared with a treatment-technique limit of 1 NTU, and reported that 100% of monthly measurements were below 0.3 NTU. The report also states that water typically leaves the plant at approximately 0.04 NTU.

The report does not provide a general warning that Northbrook’s municipal water has persistent taste, odor, discoloration, or clarity problems. Personal preferences regarding taste and presentation remain separate from regulatory compliance.

Illinois EPA considers surface-water sources susceptible to potential pollution because contaminants can migrate through surface water. Northbrook’s offshore Lake Michigan intakes are positioned far enough from shore that shoreline point sources are not normally considered a water-quality factor. However, the source-water assessment identifies possible seasonal influence from stormwater runoff and wet-weather flows associated with the North Shore Channel under certain current conditions.

Older properties may contain lead service lines or plumbing components. Northbrook advises residents concerned about lead to review their service-line material, use cold water for drinking and cooking, flush stagnant water, consider an appropriately certified lead-reduction filter, and obtain testing through an Illinois EPA-certified laboratory when warranted. 

The Consumer Confidence Report includes historical and follow-up monitoring for PFAS. The table reports finished-water PFOA and PFOS results generally near or below the laboratory reporting level, including finished-water results from 2025 ranging from below 2.0 to 2.3 ng/L for PFOA and from below 1.9 to 2.2 ng/L for PFOS. The report attributes detected PFAS to the Lake Michigan source rather than Northbrook’s treatment process.

The report’s PFAS regulatory discussion reflects earlier guidance and contains language that is no longer fully current. U.S. EPA established federal drinking-water limits for PFOA and PFOS in 2024, and in May 2026 proposed retaining those limits while potentially extending the compliance date. Illinois EPA has also continued developing and applying state PFAS protections. Residents should therefore consult current U.S. EPA, Illinois EPA, and Village notices rather than relying exclusively on older regulatory descriptions in the report. (US EPA)

The report also advises that certain people—including some infants, older adults, transplant recipients, people undergoing chemotherapy, and people with immune-system disorders—may be more vulnerable to microbial contaminants and should seek guidance from their healthcare providers.