01The verdict: is Windsor water safe?
Windsor's tap water meets most EPA standards but has areas that warrant attention. With a grade of A- (89.5/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 1 water system serves approximately 4,607 residents using groundwater (wells).
1 unresolved violation on record
EPA records show an open compliance item for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Top half in Wisconsin
Windsor ranks #93 of 441 graded Wisconsin cities.
See the comparison ↓A flood-prone service area
3 federal disaster declarations on record. After severe weather, watch for boil-water advisories.
See the risk factors ↓Windsor's drinking water received a grade of A- (89.5 out of 100), indicating good water quality. The city's 1 water system serves approximately 4,607 residents using groundwater.
Lead levels were measured at 5.5 ppb (90th percentile), which is within EPA limits but above recommended levels. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 4 violations on record, including 1 health-based violation. 1 remains unresolved.
Windsor ranks #93 out of 441 cities in Wisconsin for water quality, placing it above average in the state. Windsor 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. While lead levels are within EPA limits, they are above the recommended 5 ppb threshold that health organizations consider ideal. A point-of-use filter adds an extra layer of protection.
02What's in Windsor's water
Every contaminant flagged in Windsor, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
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. | 5.5 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Wisconsin
Cities ranked by compounds detected Cu Copper in Wisconsin
Cities ranked by 90th-percentile copper
03Windsor's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 4 violations on record, including 1 health-based violation. 1 remains unresolved.
All ten of the last ten years were clean — no EPA violations recorded for Windsor.
▲ Up 3.1 ppb since 1993. Latest reading: 5.5 ppb (2023) — 37% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Windsor's water comes from
Windsor's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
1 system
1 water system, operated under local government ownership.
4,607 people
Residents served across Windsor's service area.
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 4,607 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| WINDSOR WATER UTILITY SOUTH | WI1130267 | 4,607 | Groundwater |
Water bodies near Windsor
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on Windsor's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Industrial discharge
5 facilities within 10 miles reported 0 lb released to surface water in the latest EPA Toxics Release Inventory. Proximity doesn't equal tap contamination — treatment and hydrology decide — but it's pressure on the watershed.
Flood & storm history
3 federal disaster declarations on record for Dane County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Dane County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Windsor compares
Scores for nearby Wisconsin cities on one line, with the average marked.
dashed line = Wisconsin average (65/100)
Windsor scores 89.5/100 — above the Wisconsin average of 65/100. It outscores 8 of 10 nearby cities. Full Wisconsin rankings →
90.2 / 100FMadison, WI
35.4 / 100DGreen Bay, WI
54 / 100CRacine, WI
69.5 / 100DKenosha, WI
45.8 / 100DWaukesha, WI
47.1 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Windsor's water — not generic advice.
Filter drinking & cooking water
Basic carbon filter for extra protection. Lead detected at 5.5 ppb
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for Windsor alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Windsor, WI tap water safe to drink?
Windsor's water quality earned a grade of A- (89.5/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #93 out of 441 cities tested in Wisconsin.
What contaminants are in Windsor's water?
Lead was measured at 5.5 ppb (90th percentile). 4 violations are on record.
How is Windsor'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 Windsor?
While lead levels are within EPA limits, a filter adds extra protection. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Windsor's water come from?
Windsor's water is sourced from Groundwater. The city has 1 water system serving approximately 4,607 residents.
What health violations has Windsor's water system had?
Windsor has 1 health-based violation on record. The most recent violation was recorded in November 1994. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 1 violation remains unresolved.
Is Windsor's groundwater at risk of contamination?
Windsor 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 4 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 Windsor's water compare to other cities?
Windsor ranks #93 out of 441 cities in Wisconsin (better than 79% of state cities) and #2753 out of 15382 cities nationally (82th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.