01The verdict: is Janesville water safe?
Based on EPA testing data, Janesville's tap water is generally safe to drink. The water system earned a grade of A+ (96.1/100), meeting federal drinking water standards across key contaminant categories. The city's 1 water system serves approximately 1,200 residents using groundwater (wells).
Nothing over a legal limit
Every contaminant measured in Janesville's water is within its EPA limit, and no violations are unresolved.
See the testing ↓Lead is well under the limit
90th-percentile lead is 0.7 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓A flood-prone service area
4 federal disaster declarations on record. After severe weather, watch for boil-water advisories.
See the risk factors ↓Janesville's drinking water received a grade of A+ (96.1 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 1,200 residents using groundwater.
Lead levels were measured at 0.7 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 8 violations on record, including 5 health-based violations. All violations have been resolved.
Janesville ranks #9 out of 513 cities in Michigan for water quality, placing it one of the best in the state. Janesville 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, Janesville may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Janesville's water
Every contaminant flagged in Janesville, 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. | 0.7 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Michigan
Cities ranked by compounds detected Cu Copper in Michigan
Cities ranked by 90th-percentile copper
03Janesville'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 8 violations on record, including 5 health-based violations. All violations have been resolved.
All ten of the last ten years were clean — no EPA violations recorded for Janesville.
▼ Down 2.5 ppb since 1993. Latest reading: 0.67 ppb (2024) — 4% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Janesville's water comes from
Janesville'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 private ownership.
1,200 people
Residents served across Janesville'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 private ownership and serves approximately 1,200 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| ROCKVALE MHP | WI1540126 | 1,200 | Groundwater |
Water bodies near Janesville
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on Janesville'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.
Flood & storm history
4 federal disaster declarations on record for Oakland County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
06How Janesville compares
Scores for nearby Michigan cities on one line, with the average marked.
dashed line = Michigan average (70/100)
Janesville scores 96.1/100 — above the Michigan average of 70/100. It outscores 10 of 10 nearby cities. Full Michigan rankings →
84.1 / 100BGrand Rapids, MI
70.2 / 100DAnn Arbor, MI
51.5 / 100CLansing, MI
57.3 / 100FKalamazoo, MI
35 / 100DFlint, MI
45.8 / 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 Janesville's water — not generic advice.
A basic carbon filter still helps
Janesville'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 Janesville alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Janesville, MI tap water safe to drink?
Janesville's water quality earned a grade of A+ (96.1/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #9 out of 513 cities tested in Michigan.
What contaminants are in Janesville's water?
Lead was measured at 0.7 ppb (90th percentile). 8 violations are on record.
How is Janesville'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 Janesville?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Janesville's water come from?
Janesville's water is sourced from Groundwater. The city has 1 water system serving approximately 1,200 residents.
What health violations has Janesville's water system had?
Janesville has 5 health-based violations on record. The most recent violation was recorded in August 2010. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. All health violations have been resolved.
Is Janesville's groundwater at risk of contamination?
Janesville 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 8 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 Janesville's water compare to other cities?
Janesville ranks #9 out of 513 cities in Michigan (better than 98% of state cities) and #226 out of 15382 cities nationally (99th percentile). The grade of A+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Janesville's small water system affect quality?
Janesville's system serves approximately 1,200 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 8 violations on record.