City water profile
Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for Joliet, Illinois.
Median indexed hardness
320PPM
6 indexed ZIPs
Range 320–320.5 PPM
City summary
Joliet has 6 published ZIP profiles across Will County. The indexed median is 320 PPM, compared with 285 PPM across Illinois.
Among the 913 Illinoiscities with an indexed median, Joliet ranks #182from highest to lowest. Across all 1,065 state ZIP profiles, available estimates run from 115to 408 PPM.
The 320–320.5 PPM range shows how much the available ZIP estimates vary within the city label.
Hardness distribution
6 of 6 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.
Evidence quality
Confidence labels
Observation window: May 30, 2017 to May 13, 2026.
ZIP directory
Open a ZIP for site-level provenance and measurements.
ZIP code
320 PPM
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ZIP code
320 PPM
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ZIP code
320 PPM
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ZIP code
320 PPM
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ZIP code
320 PPM
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ZIP code
320.5 PPM
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Public water systems
PWSID IL1970450
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1977490
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1975480
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1977910
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1975930
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1975880
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1970460
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1977210
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1977730
The system names this served city; Census place overlap links the city to this ZCTA.
PWSID IL1970465
The system names this served city; Census place overlap links the city to this ZCTA.
Compliance history
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 |
|---|---|---|---|
| Chlorine | IL1977730 | Mar 1, 2026 | Archived |
| Revised Total Coliform Rule | IL1977730 | Mar 1, 2026 | Archived |
| Revised Total Coliform Rule | IL1975105 | Mar 1, 2026 | Archived |
| Chlorine | IL1975105 | Mar 1, 2026 | Archived |
| Public Notice | IL1975105 | Jan 14, 2026 | Unaddressed |
| Public Notice | IL1975105 | Jan 14, 2026 | Unaddressed |
| Public Notice | IL1975105 | Jan 14, 2026 | Unaddressed |
| Public Notice | IL1975105 | Jan 14, 2026 | Unaddressed |
| Chlorine | IL1977490 | Jan 1, 2026 | Resolved |
| Revised Total Coliform Rule | IL1977490 | Jan 1, 2026 | Resolved |
Practical next steps
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Questions people ask
The indexed city median is 320 PPM. Open the ZIP report to verify the distance and confidence behind that estimate.
Compliance history is utility-wide and cannot guarantee conditions at every tap. Check current notices and test when address-specific evidence is needed.
Choose treatment only after confirming the problem at the property. A softener targets hardness; contaminant treatment requires a matching, verified performance claim.