Is tap water safe in Naperville?

EPA SDWIS shows no active health-based violation in this profile's reporting window. That is not the same as proving every contaminant is absent, and federal data can lag state and utility records.

How hard is the water in Naperville, IL?

Nearby USGS observations produce an estimate of 245 ppm (14.3 grains per gallon), classified as very hard. This is not a tap measurement.

Do I need a water softener in ZIP code 60540?

At 245 ppm, a correctly sized whole-house softener can reduce scale buildup and hard-water spotting. Treatment for hardness does not remove all health-related contaminants.

City water profile

Naperville water quality

Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for Naperville, Illinois.

Median indexed hardness

245PPM

4 indexed ZIPs

Range 245–245 PPM

State comparison: 40 PPM below
State hardness rank: #796 of 913
Matched utilities: 1
Active health records: 0

City summary

What the indexed records say

Naperville has 4 published ZIP profiles across Dupage County and Will County. The indexed median is 245 PPM, compared with 285 PPM across Illinois.

Among the 913 Illinoiscities with an indexed median, Naperville ranks #796from highest to lowest. Across all 1,065 state ZIP profiles, available estimates run from 115to 408 PPM.

The 245–245 PPM range shows how much the available ZIP estimates vary within the city label.

Hardness distribution

How local ZIP estimates compare

Soft0 ZIPs

Moderately hard0 ZIPs

Hard0 ZIPs

Very hard4 ZIPs

4 of 4 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.

Evidence quality

Distance, dates, and confidence

Median nearest distance: 18.1 miles
Profiles with evidence: 4/4

Confidence labels

High: 0Moderate: 4Low: 0

Naperville

PWSID IL0434670

Surface water

System population served: 156,406
Last reported: May 27, 2026

The system names this served city; Census place overlap links the city to this ZCTA.

Compliance history

What EPA records show

No active health-based violation appears among the associated systems in the represented EPA reporting quarter. This does not mean every contaminant was tested at every tap.

Record	System	Period	Status
Total Haloacetic Acids (HAA5)	IL0434670	Apr 1, 2023	Resolved
Hexachlorocyclopentadiene	IL0434670	Jan 1, 2023	Archived
Methoxychlor	IL0434670	Jan 1, 2023	Archived
Heptachlor epoxide	IL0434670	Jan 1, 2023	Archived
Atrazine	IL0434670	Jan 1, 2023	Archived
Toxaphene	IL0434670	Jan 1, 2023	Resolved
HEXACHLOROBENZENE	IL0434670	Jan 1, 2023	Archived
Benzo(a)pyrene	IL0434670	Jan 1, 2023	Resolved
Di(2-ethylhexyl) adipate	IL0434670	Jan 1, 2023	Archived
Chlordane	IL0434670	Jan 1, 2023	Resolved

Practical next steps

Move from index to evidence

1. Open your ZIP. Check distance, dates, confidence, and the associated utility.
2. Read the current CCR. Confirm source water, detections, limits, ranges, and notices.
3. Test the tap when needed. Confirm health concerns or treatment sizing with the right method.

Continue comparing

Other Illinois communities

Addison

Dupage County

245 PPM median

Aurora

Dupage County

245 PPM median

Bartlett

Dupage County

247 PPM median

Bensenville

Dupage County

247 PPM median

Bloomingdale

Dupage County

247 PPM median

Burr Ridge

Dupage County

247 PPM median

Search all 913 Illinois cities →

Questions people ask

About water in Naperville

Is the water hard?

The indexed city median is 245 PPM. Open the ZIP report to verify the distance and confidence behind that estimate.

Is the tap water safe?

Compliance history is utility-wide and cannot guarantee conditions at every tap. Check current notices and test when address-specific evidence is needed.

Do I need treatment?

Choose treatment only after confirming the problem at the property. A softener targets hardness; contaminant treatment requires a matching, verified performance claim.