Is Mequon, WI Tap Water Safe to Drink?
Graded F — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
40/100
waterverge.com Mequon, WI — Water Quality Report
Mequon's drinking water received a grade of F (40 out of 100), indicating failing water quality. The city's 23 water systems serve approximately 16,575 residents using purchased surface water.
Lead levels were measured at 0.5 ppb (90th percentile), well within EPA limits. PFAS testing under UCMR 5 found no detectable forever chemicals.
The system has 437 violations on record, including 21 health-based violations. 155 remain unresolved.
What to know about Mequon's water
Mequon ranks #440 out of 446 cities in Wisconsin for water quality, placing it among the lowest-rated in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
The system has seen 33 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Mequon, WI water safe to drink?
Mequon's drinking water has significant quality concerns based on EPA testing data. With a grade of F (40/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 23 water systems serve approximately 16,575 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Mequon
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Mequon's water quality assessment. Grade: F (40/100).
Contaminants: LEAD AND COPPER RULE REVISIONS.
Contaminants: Lead and Copper Rule.
5 health-based. Contaminants: LEAD AND COPPER RULE REVISIONS, Public Notice.
Federal disaster declaration (FEMA DR-4402). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3249). Hurricane event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Mequon's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Mequon's water system has 437 total violations on record, including 21 health-based violations. 155 remain unresolved. 33 violations were issued in the last 5 years.
Flood & environmental risk
Ozaukee County has experienced 5 federally declared disasters since 1973. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Cedar Creek, Milwaukee River, Lincoln Creek @ Sherman Boulevard, Menomonee River, Little Menomonee River.
Where does Mequon's water come from?
Mequon's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 23 water systems serving approximately 16,575 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Cedar Creek (river), Milwaukee River (river), Lincoln Creek @ Sherman Boulevard (river), Menomonee River (river), Little Menomonee River (river).
What Mequon residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Mequon's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Mequon's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Forever chemicals overview
National PFAS report →Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Mequon
Industrial polluters nearby
Reported releases to surface water by facilities near Mequon, ranked by pounds discharged annually.
Total reported releases to surface water: 12 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
KESHAR CASTING LLC DBA SUPREME CASTING MILWAUKEE, WI53223 | Copper | 12 | 3.5 mi |
FLINT HILLS RESOURCES PINE BEND LLC MILWAUKEE TERMINAL MILWAUKEE, WI53224 | Polycyclic aromatic compounds | 0 | 2.2 mi |
CHEMSTATION OF WISCONSIN BUTLER, WI53007 | — | — | 7.2 mi |
CARLSON TOOL & MANUFACTURING CORP. CEDARBURG, WI53012 | — | — | 5.0 mi |
KEMPS LLC CEDARBURG, WI53012 | — | — | 5.2 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Mequon
Superfund sites nearby
Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
- MOSS AMERICAN CO INC KERR MCGEE OIL CO2.7 mi
- LAUER I SANITARY LANDFILL3.4 mi
- AMCAST INDUSTRIAL CORPORATION5.6 mi
Source: EPA Superfund National Priorities List
Flood & disaster history
Ozaukee County has experienced 5 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Mequon's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.5 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.50 | 1.3 | mg/L | Inorganic | Over Limit |
| 11Cl-PF3OUdS | ND | HI | µg/L | PFAS | Not Detected |
| 4:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 6:2 FTS 6:2 FTSPFAS A fluorotelomer sulfonate commonly found at sites contaminated with aqueous film-forming foam (AFFF) used in firefighting. Health EffectsPotential liver toxicity and endocrine disruption. Less studied but identified as a contaminant of concern. EPA LimitNo individual MCL (not yet regulated) Common SourcesFirefighting foam (AFFF), airports, military bases, and industrial facilities. | ND | HI | µg/L | PFAS | Not Detected |
| 8:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 9Cl-PF3ONS | ND | HI | µg/L | PFAS | Not Detected |
| ADONA | ND | HI | µg/L | PFAS | Not Detected |
| HFPO-DA HFPO-DA (GenX)PFAS A replacement for PFOA in manufacturing, marketed as safer but still a persistent "forever chemical." Also known as GenX. Health EffectsLiver and kidney effects, reproductive toxicity, immune system effects, and potential cancer risk. EPA Limit10 ppt MCL Common SourcesFluoropolymer manufacturing (used as PFOA replacement), industrial wastewater discharge. | ND | 0.01 | µg/L | PFAS | Not Detected |
| lithium LithiumInorganic A naturally occurring alkali metal found in groundwater. Monitored under UCMR 5 to assess occurrence in drinking water. Health EffectsKidney effects at high doses. Low-level exposure effects under study; some research suggests neurological effects. EPA LimitNo MCL (monitoring only under UCMR 5) Common SourcesNatural mineral deposits, geothermal water, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| NEtFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| NFDHA | ND | HI | µg/L | PFAS | Not Detected |
| NMeFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| PFBA PFBAPFAS One of the shortest-chain PFAS compounds. Very mobile in water and difficult to remove with standard filtration. Health EffectsThyroid effects, potential developmental toxicity. Shorter half-life in body than long-chain PFAS. EPA LimitNo individual MCL (not yet regulated) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and firefighting foam. | ND | HI | µg/L | PFAS | Not Detected |
| PFBS PFBSPFAS A short-chain PFAS used as a replacement for PFOS. While it clears the body faster than long-chain PFAS, it still persists in the environment. Health EffectsThyroid effects, reproductive and developmental toxicity, kidney effects. EPA LimitPart of Hazard Index (1.0) Common SourcesIndustrial discharge, firefighting foam, and as a replacement chemical in manufacturing. | ND | HI | µg/L | PFAS | Not Detected |
| PFDA | ND | HI | µg/L | PFAS | Not Detected |
| PFDoA | ND | HI | µg/L | PFAS | Not Detected |
| PFEESA | ND | HI | µg/L | PFAS | Not Detected |
| PFHpA PFHpAPFAS A medium-chain PFAS compound found in various environmental samples. Less studied than PFOA/PFOS but still considered a contaminant of concern. Health EffectsLiver effects, potential developmental toxicity, and endocrine disruption. EPA LimitPart of Hazard Index (1.0) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFHpS | ND | HI | µg/L | PFAS | Not Detected |
| PFHxA PFHxAPFAS A short-chain PFAS replacement chemical widely used after manufacturers phased out longer-chain PFAS. Very commonly detected in water. Health EffectsLiver and kidney effects, potential thyroid disruption. Considered less toxic than long-chain PFAS but still persistent. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial processes, firefighting foam (AFFF), food packaging, and textile treatment. | ND | HI | µg/L | PFAS | Not Detected |
| PFHxS PFHxSPFAS A medium-chain PFAS found in firefighting foam and consumer products. It has a long half-life in the human body, similar to long-chain PFAS. Health EffectsImmune system effects, thyroid disruption, and potential reproductive and developmental harm. EPA LimitPart of Hazard Index (1.0) Common SourcesFirefighting foam (AFFF), waterproof textiles, food packaging, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| PFMBA | ND | HI | µg/L | PFAS | Not Detected |
| PFMPA | ND | HI | µg/L | PFAS | Not Detected |
| PFNA PFNAPFAS A long-chain PFAS compound used in manufacturing fluoropolymers. It bioaccumulates in the body and is very persistent in the environment. Health EffectsDevelopmental effects, liver toxicity, immune suppression, and potential cancer risk. EPA LimitPart of Hazard Index (1.0) Common SourcesFluoropolymer manufacturing, industrial emissions, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFOA PFOAPFAS A long-chain PFAS ("forever chemical") once widely used in nonstick coatings and firefighting foam. It persists in the body and environment for years. Health EffectsLinked to kidney and testicular cancer, thyroid disease, elevated cholesterol, and reproductive issues. EPA Limit4.0 ppt MCL Common SourcesIndustrial discharge, firefighting foam (AFFF), nonstick cookware manufacturing, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFOS PFOSPFAS A long-chain PFAS compound historically used in stain-resistant coatings and firefighting foam. One of the most studied and persistent PFAS chemicals. Health EffectsLiver damage, immune system suppression, thyroid disruption, increased cholesterol, and potential cancer risk. EPA Limit4.0 ppt MCL Common SourcesFirefighting foam (AFFF), industrial sites, stain-resistant fabric treatments, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFPeA PFPeAPFAS A short-chain PFAS compound commonly detected in drinking water. One of the most frequently found PFAS in UCMR 5 monitoring. Health EffectsLess studied than PFOA/PFOS. Potential liver and thyroid effects. Research is ongoing. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial discharge, firefighting foam degradation, and consumer products. | ND | HI | µg/L | PFAS | Not Detected |
| PFPeS | ND | HI | µg/L | PFAS | Not Detected |
| PFTA | ND | HI | µg/L | PFAS | Not Detected |
| PFTrDA | ND | HI | µg/L | PFAS | Not Detected |
| PFUnA | ND | HI | µg/L | PFAS | Not Detected |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Mequon compares by contaminant
Explore where Mequon ranks among all Wisconsin cities for specific contaminants.
Water source & infrastructure
Where Mequon's water comes from
Mequon's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 16,575 people through 23 water systems.
Water bodies near Mequon
Mequon is located near 5 notable water bodies. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Mequon
| System Name | PWSID | Population | Source |
|---|---|---|---|
| MEQUON WATER UTILITY | WI2460112 | 11,152 | SWP |
| CONCORDIA UNIVERSITY | WI2460118 | 1,500 | GW |
| MEQUON TRAIL TOWNHOMES | WI2460817 | 615 | GW |
| HUNTINGTON PARK | WI2460151 | 600 | GW |
| BEECHWOOD FARMS ESTATES | WI2460791 | 300 | GW |
| WESTCHESTER LAKES SUBDIVISION | WI2460794 | 300 | GW |
| PARK PLACE SUBDIVISION | WI2460066 | 260 | GW |
| BRIGHTON RIDGE SUBDIVISION | WI2460973 | 200 | GW |
| PINES SUBDIVISION | WI2460982 | 200 | GW |
| HADDONSTONE SUBDIVISION | WI2460694 | 195 | GW |
| COUNTRY TERRACE CONDO HOMES | WI2460128 | 160 | GW |
| VINTAGE ESTATES | WI2460705 | 130 | GW |
| KENILWORTH SUBD | WI2460796 | 120 | GW |
| MEQUON ON THE SQUARE CONDOMINIUM OWNERS ASSOCIATION INC | WI2460955 | 110 | GW |
| RAVINE FARMS HM OWNERS ASSOC | WI2460124 | 100 | GW |
| RIVER LAKE SUBDIVISION | WI2460685 | 100 | GW |
| WYNGATE SUBDIVISION | WI2460781 | 100 | GW |
| WOODRIDGE ESTATES | WI2460824 | 100 | GW |
| HIGHLAND COLONY ESTATES CONDO | WI2460120 | 88 | GW |
| RIVER TRAILS ESTATES WATER USERS | WI2460680 | 84 | GW |
| MEQUON COLONY ESTATES | WI2460132 | 75 | GW |
| MEQUON PARC APARTMENTS LLC | WI2460159 | 60 | GW |
| MEQUON WATER TRUST | WI2460131 | 26 | GW |
How Mequon compares
Full Wisconsin rankings →Mequon's score of 40/100 is below the average of 65/100 among major Wisconsin cities. It outscores 1 of 10 nearby cities. 9 of 10 nearby cities score higher.
Nearby cities
View Wisconsin rankings →About Mequon, WI
Wikipedia →Mequon is the most populous city in Ozaukee County, Wisconsin, United States. The population was 25,142 at the 2020 census. Located on Lake Michigan's western shore with significant commercial developments along Interstate 43, the community is a suburb in the Milwaukee metropolitan area. Despite being the third-largest city in Wisconsin by land area, approximately half of Mequon's land is undeveloped, and agriculture plays a significant role in the local economy.
Learn more about your water
Guides and resources related to Mequon's water quality findings.
Explore water quality across Ozaukee
Frequently asked questions
Is Mequon, WI tap water safe to drink?
Mequon's water quality earned a grade of F (40/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #440 out of 446 cities tested in Wisconsin.
What contaminants are in Mequon's water?
Lead was measured at 0.5 ppb (90th percentile). No PFAS compounds were detected. 437 violations are on record.
How is Mequon's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Mequon?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Mequon's water come from?
Mequon's water is sourced from Purchased surface water. The city has 23 water systems serving approximately 16,575 residents.
What health violations has Mequon's water system had?
Mequon has 21 health-based violations on record. The most recent violation was recorded in July 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 155 violations remain unresolved.
How does Mequon's water compare to other cities?
Mequon ranks #440 out of 446 cities in Wisconsin (better than 1% of state cities) and #15189 out of 15744 cities nationally (4th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.