01The verdict: is Tonica water safe?
Tonica's drinking water has significant quality concerns based on EPA testing data. With a grade of A (91.5/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 705 residents using groundwater (wells).
5 unresolved violations on record
EPA records show open compliance items for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 0.0 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓Check back after the next refresh
EPA data updates on a rolling basis; we fold in new samples and violations every month.
Get alerts ↓Tonica's drinking water received a grade of A (91.5 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 705 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 30 violations on record, including 16 health-based violations. 5 remain unresolved.
Tonica ranks #102 out of 882 cities in Illinois for water quality, placing it above average in the state. Tonica 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, Tonica may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Tonica's water
Every contaminant flagged in Tonica, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
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 |
Cities ranked by 90th-percentile lead PF PFAS in Illinois
Cities ranked by compounds detected Cu Copper in Illinois
Cities ranked by 90th-percentile copper
03Tonica's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 30 violations on record, including 16 health-based violations. 5 remain unresolved.
All ten of the last ten years were clean — no EPA violations recorded for Tonica.
▼ Down 0 ppb since 1993. Latest reading: 0 ppb (2025) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Tonica's water comes from
Tonica's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
1 system
1 water system, operated under local government ownership.
705 people
Residents served across Tonica's service area.
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 705 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| TONICA | IL0991150 | 705 | Groundwater |
Water bodies near Tonica
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on Tonica's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Industrial discharge
5 facilities within 10 miles reported 1k lb released to surface water in the latest EPA Toxics Release Inventory. Proximity doesn't equal tap contamination — treatment and hydrology decide — but it's pressure on the watershed.
Superfund proximity
2 National Priorities List sites within 10 miles. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
06How Tonica compares
Scores for nearby Illinois cities on one line, with the average marked.
dashed line = Illinois average (55/100)
Tonica scores 91.5/100 — above the Illinois average of 55/100. It outscores 10 of 10 nearby cities. Full Illinois rankings →
35.2 / 100DAurora, IL
45.5 / 100FJoliet, IL
38.5 / 100BNaperville, IL
81.2 / 100FRockford, IL
38.4 / 100FKankakee, IL
42.6 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Tonica's water — not generic advice.
A basic carbon filter still helps
Tonica's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Tonica alerts
We refresh EPA data monthly and surface new violations, advisories, and boil-water notices for your county on this page.
All water alerts →Frequently asked questions
Is Tonica, IL tap water safe to drink?
Tonica's water quality earned a grade of A (91.5/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #102 out of 882 cities tested in Illinois.
What contaminants are in Tonica's water?
Lead was measured at 0.0 ppb (90th percentile). 30 violations are on record.
How is Tonica'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 Tonica?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Tonica's water come from?
Tonica's water is sourced from Groundwater. The city has 1 water system serving approximately 705 residents.
What health violations has Tonica's water system had?
Tonica has 16 health-based violations on record. The most recent violation was recorded in July 2013. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 5 violations remain unresolved.
Is Tonica's groundwater at risk of contamination?
Tonica 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 30 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 Tonica's water compare to other cities?
Tonica ranks #102 out of 882 cities in Illinois (better than 88% of state cities) and #1673 out of 15382 cities nationally (89th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Tonica's small water system affect quality?
Tonica's system serves approximately 705 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 30 violations on record.