Is Mosinee, 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 ↓
43/100
waterverge.com Mosinee, WI — Water Quality Report
Mosinee's drinking water received a grade of F (43 out of 100), indicating failing water quality. The city's 5 water systems serve approximately 4,766 residents using groundwater.
Lead levels were measured at 1.8 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 173 violations on record, including 15 health-based violations. 42 remain unresolved.
What to know about Mosinee's water
Mosinee ranks #434 out of 446 cities in Wisconsin for water quality, placing it among the lowest-rated in the state.
Mosinee relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
The system has seen 27 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Mosinee, WI water safe to drink?
Mosinee's drinking water has significant quality concerns based on EPA testing data. With a grade of F (43/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 5 water systems serve approximately 4,766 residents using groundwater (wells).
Recent water quality updates for Mosinee
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Mosinee's water quality assessment. Grade: F (43/100).
Contaminants: LEAD AND COPPER RULE REVISIONS, Consumer Confidence Rule.
Contaminants: Revised Total Coliform Rule.
Contaminants: Lead and Copper Rule.
Federal disaster declaration (FEMA DR-3249). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-376). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Mosinee'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
Mosinee's water system has 173 total violations on record, including 15 health-based violations. 42 remain unresolved. 27 violations were issued in the last 5 years.
Flood & environmental risk
Marathon County has experienced 2 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 Wisconsin River.
Where does Mosinee's water come from?
Mosinee's drinking water comes from groundwater (wells), supplied by 5 water systems serving approximately 4,766 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Wisconsin River (river).
What Mosinee residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Mosinee'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.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Mosinee
Industrial polluters nearby
Reported releases to surface water by facilities near Mosinee, ranked by pounds discharged annually.
Total reported releases to surface water: 61,973 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
AHLSTROM MOSINEE LLC MOSINEE, WI54455 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 46,275 | 0.5 mi |
DOMTAR PAPER CO LLC ROTHSCHILD, WI54474 | Manganese And Manganese Compounds | 13,394 | 7.1 mi |
BORREGAARD USA INC. ROTHSCHILD, WI54474 | Barium compounds (except for barium sulfate (CAS No. 7727-43-7)) | 1,235 | 7.2 mi |
WESTON POWER PLANT MOSINEE, WI54455 | Barium compounds (except for barium sulfate (CAS No. 7727-43-7)) | 1,019 | 4.9 mi |
KERRY INC. ROTHSCHILD ROTHSCHILD, WI54474 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 50 | 5.6 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
Marathon County has experienced 2 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 Mosinee'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. | 1.8 | 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. | 1.40 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Mosinee compares by contaminant
Explore where Mosinee ranks among all Wisconsin cities for specific contaminants.
Water source & infrastructure
Where Mosinee's water comes from
Mosinee's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 4,766 people through 5 water systems.
Water bodies near Mosinee
Mosinee is located near 1 notable water body. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Mosinee
| System Name | PWSID | Population | Source |
|---|---|---|---|
| MOSINEE WATERWORKS | WI7370159 | 3,406 | GW |
| MOSINEE EAST SYSTEM | WI7372480 | 1,046 | GW |
| MAIZEFIELD MHC (MANUFACTURED HOME COMMUNITY) | WI7370157 | 145 | GW |
| DEER TRAIL VILLAGE | WI7370158 | 120 | GW |
| EDGEWOOD COUNTRY ESTATES | WI7371500 | 49 | GW |
How Mosinee compares
Full Wisconsin rankings →Mosinee's score of 43/100 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 Mosinee, WI
Wikipedia →Mosinee is a city in Marathon County, Wisconsin, United States. It is part of the Wausau, Wisconsin Metropolitan Statistical Area. The population was 4,452 at the time of the 2020 census.
Learn more about your water
Guides and resources related to Mosinee's water quality findings.
Explore water quality across Marathon
Frequently asked questions
Is Mosinee, WI tap water safe to drink?
Mosinee's water quality earned a grade of F (43/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #434 out of 446 cities tested in Wisconsin.
What contaminants are in Mosinee's water?
Lead was measured at 1.8 ppb (90th percentile). 173 violations are on record.
How is Mosinee'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 Mosinee?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Mosinee's water come from?
Mosinee's water is sourced from Groundwater. The city has 5 water systems serving approximately 4,766 residents.
What health violations has Mosinee's water system had?
Mosinee has 15 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. 42 violations remain unresolved.
Is Mosinee's groundwater at risk of contamination?
Mosinee uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 173 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Mosinee's water compare to other cities?
Mosinee ranks #434 out of 446 cities in Wisconsin (better than 3% of state cities) and #14668 out of 15744 cities nationally (7th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.