Is the Water Safe in Naperville, IL?
The 1 public water system serving Naperville, Illinois (population 156,406) average a Water Safety Score of 88/100, with a worst grade of B. These systems have no health-based violations on record.
Safety & Violations
| Metric | Value |
|---|---|
| Average Safety Score | 88/100 (B worst) |
| Public Water Systems | 1 |
| Population Served | 156,406 |
| Health Violations | 0 |
| Monitoring Violations | 0 |
| Contaminant Exceedances | 0 |
| Enforcement Actions | 4 |
Contaminants Detected in Naperville
| Contaminant | Detected | EPA Limit (MCL) | Status |
|---|---|---|---|
| Haloacetic Acids (HAA5) | 30 ppb | 60 ppb | Within limit |
Detected levels are the highest reported across Naperville systems for each contaminant. MCL = EPA Maximum Contaminant Level, the legal safety ceiling. Source: EPA SDWIS monitoring data.
Frequently Asked Questions
The 1 public water system serving Naperville, Illinois (population 156,406) average a Water Safety Score of 88/100, with a worst grade of B. These systems have no health-based violations on record.
Monitoring data for Naperville, Illinois shows 1 distinct contaminant detected in the public water supply — Haloacetic Acids (HAA5). None exceeded the EPA Maximum Contaminant Level in the reported samples.
Naperville, Illinois is served by 1 public water system, together supplying water to roughly 156,406 people. The worst safety grade among them is B.
No. In the reported monitoring data for Naperville, no detected contaminant exceeded its EPA Maximum Contaminant Level (MCL).
The Water Safety Score (0-100, graded A-F) weighs health-based violations (40%), contaminant exceedances (30%), enforcement history (20%), and monitoring violations (10%), using EPA Safe Drinking Water Information System (SDWIS) data from the last 10 years.
Request your utility's annual Consumer Confidence Report (CCR), consider an independent test from a state-certified lab, and use an NSF-certified filter targeting any contaminant of concern. For lead specifically, run cold water 30 seconds before drinking.
More about Naperville
The 1 public water system serving Naperville, Illinois (population 156,406) average a Water Safety Score of 88/100, with a worst grade of B. These systems have no health-based violations on record.
The data source behind this answer is the EPA Safe Drinking Water Information System (SDWIS). Every figure on the page traces back to that source; the methodology page describes the inputs and the refresh cadence in full detail.
A practical caveat: the headline answer above reflects the most recent the EPA Safe Drinking Water Information System (SDWIS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.
Source: EPA Ground Water and Drinking Water, 2026.