Is Rio, WI Tap Water Safe to Drink?
Graded B+, with 5 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
83.8/100
waterverge.com Rio, WI — Water Quality Report
Rio's drinking water received a grade of B+ (83.8 out of 100), indicating good water quality. The city's 1 water system serves approximately 1,095 residents using groundwater.
Lead levels were measured at 1.4 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 18 violations on record, including 1 health-based violation. 5 remain unresolved.
What to know about Rio's water
Rio ranks #194 out of 446 cities in Wisconsin for water quality, placing it mid-range in the state.
Rio 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, Rio may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Rio, WI water safe to drink?
Rio's drinking water has significant quality concerns based on EPA testing data. With a grade of B+ (83.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 1,095 residents using groundwater (wells).
Recent water quality updates for Rio
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Rio's water quality assessment. Grade: B+ (83.8/100).
1 health-based. Contaminants: Public Notice, LEAD AND COPPER RULE REVISIONS.
Contaminants: Lead and Copper Rule.
Contaminants: Groundwater Rule.
Federal disaster declaration (FEMA DR-3249). Hurricane event — may have impacted local water infrastructure.
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 Rio's water supply.
Well within EPA limits.
Violation history
Rio's water system has 18 total violations on record, including 1 health-based violation. 5 remain unresolved. 3 violations were issued in the last 5 years.
Flood & environmental risk
Columbia County has experienced 2 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.
Where does Rio's water come from?
Rio's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 1,095 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What Rio residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Rio'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 Rio
Industrial polluters nearby
Reported releases to surface water by facilities near Rio, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
COLUMBIA ENERGY CENTER PARDEEVILLE, WI53954 | — | — | 9.1 mi |
DIDION ETHANOL LLC CAMBRIA, WI53923 | — | — | 9.0 mi |
EVERBRITE LLC PARDEEVILLE, WI53954 | — | — | 6.2 mi |
GRANDE CHEESE CO WYOCENA WYOCENA, WI53969 | — | — | 4.6 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
Columbia County has experienced 2 federally declared disasters since 1976. 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. | 1.4 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Rio compares by contaminant
Explore where Rio ranks among all Wisconsin cities for specific contaminants.
Water source & infrastructure
Where Rio's water comes from
Rio'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 1,095 people through 1 water system.
Water systems serving Rio
| System Name | PWSID | Population | Source |
|---|---|---|---|
| RIO WATERWORKS | WI1110111 | 1,095 | GW |
How Rio compares
Full Wisconsin rankings →Rio's score of 83.8/100 is above the average of 65/100 among major Wisconsin cities. It outscores 8 of 10 nearby cities.
Nearby cities
View Wisconsin rankings →About Rio, WI
Learn more about your water
Guides and resources related to Rio's water quality findings.
Explore water quality across Columbia
Frequently asked questions
Is Rio, WI tap water safe to drink?
Rio's water quality earned a grade of B+ (83.8/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #194 out of 446 cities tested in Wisconsin.
What contaminants are in Rio's water?
Lead was measured at 1.4 ppb (90th percentile). 18 violations are on record.
How is Rio'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 Rio?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Rio's water come from?
Rio's water is sourced from Groundwater. The city has 1 water system serving approximately 1,095 residents.
What health violations has Rio's water system had?
Rio has 1 health-based violation on record. The most recent violation was recorded in October 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 5 violations remain unresolved.
Is Rio's groundwater at risk of contamination?
Rio 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 18 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 Rio's water compare to other cities?
Rio ranks #194 out of 446 cities in Wisconsin (better than 57% of state cities) and #6277 out of 15744 cities nationally (60th percentile). The grade of B+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Rio's small water system affect quality?
Rio's system serves approximately 1,095 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 18 violations on record.