Is Deerfield, WI Tap Water Safe to Drink?
Graded B — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
77.5/100
waterverge.com Deerfield, WI — Water Quality Report
Deerfield's drinking water received a grade of B (77.5 out of 100), indicating good water quality. The city's 2 water systems serve approximately 2,575 residents using groundwater.
Lead levels were measured at 3.1 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 37 violations on record, including 7 health-based violations. 11 remain unresolved.
What to know about Deerfield's water
Deerfield ranks #295 out of 446 cities in Wisconsin for water quality, placing it below average in the state.
Deerfield 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.
As a small community water system, Deerfield may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 7 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Deerfield, WI water safe to drink?
Deerfield's drinking water has significant quality concerns based on EPA testing data. With a grade of B (77.5/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 2,575 residents using groundwater (wells).
Recent water quality updates for Deerfield
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Deerfield's water quality assessment. Grade: B (77.5/100).
Contaminants: Revised Total Coliform Rule.
Contaminants: Consumer Confidence Rule.
Contaminants: Lead and Copper Rule.
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 Deerfield'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
Deerfield's water system has 37 total violations on record, including 7 health-based violations. 11 remain unresolved. 7 violations were issued in the last 5 years.
Flood & environmental risk
Dane County has experienced 3 federally declared disasters since 1976. 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 Yahara River @ Forton Street Bridge @ Stoughton,Wi.
Where does Deerfield's water come from?
Deerfield's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 2,575 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Yahara River @ Forton Street Bridge @ Stoughton,Wi (river).
What Deerfield residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Deerfield'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.
Run cold water for 30 seconds before drinking, especially in the morning. Lead and copper leach from household plumbing when water sits in pipes.
Deerfield'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 ↓Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Deerfield
Industrial polluters nearby
Reported releases to surface water by facilities near Deerfield, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
HYDRITE CHEMICAL CO. COTTAGE GROVE, WI53527 | — | — | 6.6 mi |
MPI ENGINEERED TECHNOLOGIES LLC DEERFIELD, WI53531 | — | — | 0.5 mi |
MPI - WIS FINEBLANKING DIV DEERFIELD, WI53531 | — | — | 0.4 mi |
FIBERDOME PRODUCTS LLC PLANT 2 LAKE MILLS, WI53551 | — | — | 9.4 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
Dane County has experienced 3 federally declared disasters since 1976. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Deerfield'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. | 3.1 | 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. | 1.84 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level (90th percentile)
Latest reading: 1.840 mg/L (2015)
EPA action level: 1.3 mg/L
See how Deerfield compares by contaminant
Explore where Deerfield ranks among all Wisconsin cities for specific contaminants.
Water source & infrastructure
Where Deerfield's water comes from
Deerfield'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 2,575 people through 2 water systems.
Water bodies near Deerfield
Deerfield is located near 1 notable water body. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Deerfield
| System Name | PWSID | Population | Source |
|---|---|---|---|
| DEERFIELD WATERWORKS | WI1130223 | 2,510 | GW |
| COUNTRY VIEW ESTATES | WI1130214 | 65 | GW |
How Deerfield compares
Full Wisconsin rankings →Deerfield's score of 77.5/100 is above the average of 65/100 among major Wisconsin cities. It outscores 6 of 10 nearby cities.
Nearby cities
View Wisconsin rankings →About Deerfield, WI
Wikipedia →Deerfield is a village in Dane County, Wisconsin, United States. The population was 2,540 at the time of the 2020 census. The village is located within the Town of Deerfield. It is part of the Madison, Wisconsin metropolitan area, and a suburb of Madison. Towns and villages near Deerfield include Stoughton, Madison, Wisconsin, Marshall, Medina, London, Lake Mills, Cambridge, and Cottage Grove, Wisconsin.
Learn more about your water
Guides and resources related to Deerfield's water quality findings.
Explore water quality across Dane
Frequently asked questions
Is Deerfield, WI tap water safe to drink?
Deerfield's water quality earned a grade of B (77.5/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #295 out of 446 cities tested in Wisconsin.
What contaminants are in Deerfield's water?
Lead was measured at 3.1 ppb (90th percentile). 37 violations are on record.
How is Deerfield'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 Deerfield?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Deerfield's water come from?
Deerfield's water is sourced from Groundwater. The city has 2 water systems serving approximately 2,575 residents.
What health violations has Deerfield's water system had?
Deerfield has 7 health-based violations on record. The most recent violation was recorded in August 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 11 violations remain unresolved.
Is Deerfield's groundwater at risk of contamination?
Deerfield 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 37 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 Deerfield's water compare to other cities?
Deerfield ranks #295 out of 446 cities in Wisconsin (better than 34% of state cities) and #8981 out of 15744 cities nationally (43th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.