Is South Wilmington, IL 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 ↓
83.1/100
waterverge.com South Wilmington, IL — Water Quality Report
South Wilmington's drinking water received a grade of B+ (83.1 out of 100), indicating good water quality. The city's 1 water system serves approximately 700 residents using groundwater.
Lead levels were measured at 0.0 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 38 violations on record, including 20 health-based violations. 5 remain unresolved.
What to know about South Wilmington's water
South Wilmington ranks #460 out of 891 cities in Illinois for water quality, placing it below average in the state.
South Wilmington 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, South Wilmington may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 9 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is South Wilmington, IL water safe to drink?
South Wilmington's drinking water has significant quality concerns based on EPA testing data. With a grade of B+ (83.1/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 700 residents using groundwater (wells).
Recent water quality updates for South Wilmington
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into South Wilmington's water quality assessment. Grade: B+ (83.1/100).
Contaminants: LEAD AND COPPER RULE REVISIONS, Lead and Copper Rule.
Contaminants: Combined Uranium.
Contaminants: Combined Uranium, Combined Radium (-226 and -228).
Federal disaster declaration (FEMA DR-4116). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3230). Hurricane event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for South Wilmington's water supply.
Well within EPA limits.
Violation history
South Wilmington's water system has 38 total violations on record, including 20 health-based violations. 5 remain unresolved. 9 violations were issued in the last 5 years.
Flood & environmental risk
Grundy County has experienced 5 federally declared disasters since 1972. 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 Kankakee River, Mazon River.
Where does South Wilmington's water come from?
South Wilmington's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 700 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Kankakee River (river), Mazon River (river).
What South Wilmington residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in South Wilmington'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.
South Wilmington'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
Flood & disaster history
Grundy County has experienced 5 federally declared disasters since 1972. 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. | 0.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how South Wilmington compares by contaminant
Explore where South Wilmington ranks among all Illinois cities for specific contaminants.
Water source & infrastructure
Where South Wilmington's water comes from
South Wilmington'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 700 people through 1 water system.
Water bodies near South Wilmington
South Wilmington is located near 2 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving South Wilmington
| System Name | PWSID | Population | Source |
|---|---|---|---|
| SOUTH WILMINGTON | IL0630650 | 700 | GW |
How South Wilmington compares
Full Illinois rankings →South Wilmington's score of 83.1/100 is above the average of 56/100 among major Illinois cities. It outscores 8 of 10 nearby cities.
Nearby cities
View Illinois rankings →About South Wilmington, IL
Learn more about your water
Guides and resources related to South Wilmington's water quality findings.
Explore water quality across Grundy
Frequently asked questions
Is South Wilmington, IL tap water safe to drink?
South Wilmington's water quality earned a grade of B+ (83.1/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #460 out of 891 cities tested in Illinois.
What contaminants are in South Wilmington's water?
Lead was measured at 0.0 ppb (90th percentile). 38 violations are on record.
How is South Wilmington'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 South Wilmington?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does South Wilmington's water come from?
South Wilmington's water is sourced from Groundwater. The city has 1 water system serving approximately 700 residents.
What health violations has South Wilmington's water system had?
South Wilmington has 20 health-based violations on record. The most recent violation was recorded in July 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 5 violations remain unresolved.
Is South Wilmington's groundwater at risk of contamination?
South Wilmington 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 38 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 South Wilmington's water compare to other cities?
South Wilmington ranks #460 out of 891 cities in Illinois (better than 48% of state cities) and #6608 out of 15744 cities nationally (58th percentile). The grade of B+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does South Wilmington's small water system affect quality?
South Wilmington's system serves approximately 700 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 38 violations on record.