Is Thiensville, WI Tap Water Safe to Drink?
Graded D, with 146 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
47/100
waterverge.com Thiensville, WI — Water Quality Report
Thiensville's drinking water received a grade of D (47 out of 100), indicating poor water quality. The city's 16 water systems serve approximately 1,045 residents using groundwater.
Lead levels were measured at 0.6 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 676 violations on record, including 30 health-based violations. 146 remain unresolved.
What to know about Thiensville's water
Thiensville ranks #423 out of 446 cities in Wisconsin for water quality, placing it among the lowest-rated in the state.
Thiensville 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, Thiensville may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 41 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Thiensville, WI water safe to drink?
Thiensville's drinking water has significant quality concerns based on EPA testing data. With a grade of D (47/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 16 water systems serve approximately 1,045 residents using groundwater (wells).
Recent water quality updates for Thiensville
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Thiensville's water quality assessment. Grade: D (47/100).
Contaminants: Lead and Copper Rule.
Contaminants: LEAD AND COPPER RULE REVISIONS, Public Notice.
Contaminants: 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 Thiensville's water supply.
Well within EPA limits.
Violation history
Thiensville's water system has 676 total violations on record, including 30 health-based violations. 146 remain unresolved. 41 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 Thiensville's water come from?
Thiensville's drinking water comes from groundwater (wells), supplied by 16 water systems serving approximately 1,045 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Cedar Creek (river), Milwaukee River (river), Lincoln Creek @ Sherman Boulevard (river), Menomonee River (river), Little Menomonee River (river).
What Thiensville residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Thiensville'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.
Thiensville'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 Thiensville
Industrial polluters nearby
Reported releases to surface water by facilities near Thiensville, ranked by pounds discharged annually.
Total reported releases to surface water: 211 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
SCHREIBER FOODS WEST BEND, WI53095 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 199 | 9.5 mi |
KESHAR CASTING LLC DBA SUPREME CASTING MILWAUKEE, WI53223 | Copper | 12 | 5.2 mi |
FLINT HILLS RESOURCES PINE BEND LLC MILWAUKEE TERMINAL MILWAUKEE, WI53224 | Polycyclic aromatic compounds | 0 | 4.7 mi |
CHEMSTATION OF WISCONSIN BUTLER, WI53007 | — | — | 9.6 mi |
CARLSON TOOL & MANUFACTURING CORP. CEDARBURG, WI53012 | — | — | 3.0 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Thiensville
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.
- AMCAST INDUSTRIAL CORPORATION3.7 mi
- MOSS AMERICAN CO INC KERR MCGEE OIL CO5.2 mi
- LAUER I SANITARY LANDFILL5.9 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.
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. | 0.6 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Thiensville compares by contaminant
Explore where Thiensville ranks among all Wisconsin cities for specific contaminants.
Water source & infrastructure
Where Thiensville's water comes from
Thiensville'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 private ownership and serves approximately 1,045 people through 16 water systems.
Water bodies near Thiensville
Thiensville is located near 5 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Thiensville
| System Name | PWSID | Population | Source |
|---|---|---|---|
| CENTURY ESTATES 1 | WI2460143 | 130 | GW |
| VILLAGE HEIGHTS | WI2460145 | 130 | GW |
| LINDEN LANE APTS 117 | WI2460142 | 90 | GW |
| LAUREL LAKES 608 | WI2460137 | 80 | GW |
| GRAND AVE APARTMENTS | WI2460640 | 80 | GW |
| ALBERTA SUBDIVISION | WI2460141 | 75 | GW |
| LINDEN LANE APTS 141 | WI2460154 | 75 | GW |
| WILLIAMSBURG 207 209 AND 214 | WI2460147 | 70 | GW |
| LAUREL LAKES 508 | WI2460150 | 50 | GW |
| WATERS EDGE CONDOMINIUM ASSOCIATION | WI2460823 | 50 | GW |
| WILLIAMSBURG 206 | WI2460148 | 48 | GW |
| HEIDEL RD APTS 139 | WI2460152 | 40 | GW |
| HEIDEL RD APTS 152 | WI2460158 | 40 | GW |
| WILLIAMSBURG 220 | WI2460067 | 32 | GW |
| VILLAGE GLEN APTS | WI2460140 | 30 | GW |
| RIVER GARDEN APTS | WI2460139 | 25 | GW |
How Thiensville compares
Full Wisconsin rankings →Thiensville's score of 47/100 is below the average of 65/100 among major Wisconsin cities. It outscores 2 of 10 nearby cities. 8 of 10 nearby cities score higher.
Nearby cities
View Wisconsin rankings →About Thiensville, WI
Learn more about your water
Guides and resources related to Thiensville's water quality findings.
Explore water quality across Ozaukee
Frequently asked questions
Is Thiensville, WI tap water safe to drink?
Thiensville's water quality earned a grade of D (47/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #423 out of 446 cities tested in Wisconsin.
What contaminants are in Thiensville's water?
Lead was measured at 0.6 ppb (90th percentile). 676 violations are on record.
How is Thiensville'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 Thiensville?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Thiensville's water come from?
Thiensville's water is sourced from Groundwater. The city has 16 water systems serving approximately 1,045 residents.
What health violations has Thiensville's water system had?
Thiensville has 30 health-based violations on record. The most recent violation was recorded in October 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 146 violations remain unresolved.
Is Thiensville's groundwater at risk of contamination?
Thiensville 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 676 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 Thiensville's water compare to other cities?
Thiensville ranks #423 out of 446 cities in Wisconsin (better than 5% of state cities) and #13777 out of 15744 cities nationally (13th percentile). The grade of D reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.