Is Darien, WI Tap Water Safe to Drink?
Graded A, with 5 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
91.7/100
waterverge.com Darien, WI — Water Quality Report
Darien's drinking water received a grade of A (91.7 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 1,573 residents using groundwater.
Lead levels were measured at 0.9 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 50 violations on record, including 2 health-based violations. 5 remain unresolved.
What to know about Darien's water
Darien ranks #41 out of 446 cities in Wisconsin for water quality, placing it one of the best in the state.
Darien 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, Darien may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Darien, WI water safe to drink?
Darien's drinking water has significant quality concerns based on EPA testing data. With a grade of A (91.7/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 1,573 residents using groundwater (wells).
Recent water quality updates for Darien
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Darien's water quality assessment. Grade: A (91.7/100).
Contaminants: Lead and Copper Rule.
Contaminants: Lead and Copper Rule.
Federal disaster declaration (FEMA DR-3249). Hurricane event — may have impacted local water infrastructure.
Contaminants: 1,2-Dichloroethane, 1,1,1-Trichloroethane, 1,2-Dichloropropane.
Federal disaster declaration (FEMA DR-496). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Darien's water supply.
Well within EPA limits.
Violation history
Darien's water system has 50 total violations on record, including 2 health-based violations. 5 remain unresolved.
Flood & environmental risk
Walworth County has experienced 3 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 Jackson Creek, Delavan Lake Inlet, Delavan Lake Outlet, Turtle Creek, Piscasaw Creek.
Where does Darien's water come from?
Darien's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 1,573 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Jackson Creek (river), Delavan Lake Inlet (river), Delavan Lake Outlet (river), Turtle Creek (river), Piscasaw Creek (river).
What Darien residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Darien'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.
Darien'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 Darien
Industrial polluters nearby
Reported releases to surface water by facilities near Darien, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
CONAGRA FOODS PACKAGED FOODS LLC DARIEN, WI53114 | — | — | 1.5 mi |
USG STRUCTURAL TECHNOLOGIES LLC DELAVAN, WI53115 | — | — | 5.5 mi |
PENTAIR FLOW TECHNOLOGIES DELAVAN, WI53115 | — | — | 5.0 mi |
SPX FLOW US LLC DELAVAN, WI53115 | — | — | 5.1 mi |
SPX FLOW US LLC DELAVAN, WI53115 | — | — | 5.5 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Darien
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.
- DELAVAN MUNICIPAL WELL 45.0 mi
Source: EPA Superfund National Priorities List
Flood & disaster history
Walworth County has experienced 3 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
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. | 0.9 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Darien compares by contaminant
Explore where Darien ranks among all Wisconsin cities for specific contaminants.
Water source & infrastructure
Where Darien's water comes from
Darien'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 1,573 people through 1 water system.
Water bodies near Darien
Darien is located near 5 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Darien
| System Name | PWSID | Population | Source |
|---|---|---|---|
| DARIEN WATERWORKS | WI2650057 | 1,573 | GW |
How Darien compares
Full Wisconsin rankings →Darien's score of 91.7/100 is above the average of 65/100 among major Wisconsin cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Wisconsin rankings →About Darien, WI
Wikipedia →Darien is a village in Walworth County, Wisconsin, United States. The population was 1,573 at the 2020 census. The village is located within the Town of Darien.
Learn more about your water
Guides and resources related to Darien's water quality findings.
Explore water quality across Walworth
Frequently asked questions
Is Darien, WI tap water safe to drink?
Darien's water quality earned a grade of A (91.7/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #41 out of 446 cities tested in Wisconsin.
What contaminants are in Darien's water?
Lead was measured at 0.9 ppb (90th percentile). 50 violations are on record.
How is Darien'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 Darien?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Darien's water come from?
Darien's water is sourced from Groundwater. The city has 1 water system serving approximately 1,573 residents.
What health violations has Darien's water system had?
Darien has 2 health-based violations on record. The most recent violation was recorded in July 2020. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 5 violations remain unresolved.
Is Darien's groundwater at risk of contamination?
Darien 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 50 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 Darien's water compare to other cities?
Darien ranks #41 out of 446 cities in Wisconsin (better than 91% of state cities) and #1538 out of 15744 cities nationally (90th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Darien's small water system affect quality?
Darien's system serves approximately 1,573 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 50 violations on record.