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City water profile

St. Louis water quality

Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for St. Louis, Missouri.

Median indexed hardness

255PPM

19 indexed ZIPs

Range 254–256 PPM

State comparison
19 PPM above
State hardness rank
#199 of 504
Matched utilities
1
Active health records
0

City summary

What the indexed records say

St. Louis has 19 published ZIP profiles across St. Louis City County. The indexed median is 255 PPM, compared with 236 PPM across Missouri.

Among the 504 Missouricities with an indexed median, St. Louis ranks #199from highest to lowest. Across all 556 state ZIP profiles, available estimates run from 38.3to 483 PPM.

The 254–256 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 hard19 ZIPs

19 of 19 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.

Evidence quality

Distance, dates, and confidence

Median nearest distance
14.9 miles
Profiles with evidence
19/19

Confidence labels

High: 0Moderate: 19Low: 0

Observation window: Jan 6, 2016 to Jun 9, 2026.

ZIP directory

Water reports in St. Louis

Open a ZIP for site-level provenance and measurements.

ZIP code

63101

Very Hard

255 PPM

Nearest site
16.7 mi
Confidence
Moderate

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ZIP code

63102

Very Hard

255 PPM

Nearest site
17.1 mi
Confidence
Moderate

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ZIP code

63103

Very Hard

255 PPM

Nearest site
15.7 mi
Confidence
Moderate

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ZIP code

63104

Very Hard

255 PPM

Nearest site
14.9 mi
Confidence
Moderate

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ZIP code

63106

Very Hard

255 PPM

Nearest site
16.8 mi
Confidence
Moderate

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ZIP code

63107

Very Hard

255 PPM

Nearest site
15.5 mi
Confidence
Moderate

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ZIP code

63108

Very Hard

255 PPM

Nearest site
15.3 mi
Confidence
Moderate

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ZIP code

63109

Very Hard

255 PPM

Nearest site
10.6 mi
Confidence
Moderate

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ZIP code

63110

Very Hard

255 PPM

Nearest site
13.8 mi
Confidence
Moderate

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ZIP code

63111

Very Hard

254 PPM

Nearest site
11.1 mi
Confidence
Moderate

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ZIP code

63112

Very Hard

256 PPM

Nearest site
15.4 mi
Confidence
Moderate

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ZIP code

63113

Very Hard

255 PPM

Nearest site
16.2 mi
Confidence
Moderate

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ZIP code

63115

Very Hard

256 PPM

Nearest site
14.5 mi
Confidence
Moderate

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ZIP code

63116

Very Hard

254 PPM

Nearest site
11.4 mi
Confidence
Moderate

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ZIP code

63118

Very Hard

255 PPM

Nearest site
13.6 mi
Confidence
Moderate

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ZIP code

63120

Very Hard

256 PPM

Nearest site
14.2 mi
Confidence
Moderate

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ZIP code

63139

Very Hard

255 PPM

Nearest site
12.2 mi
Confidence
Moderate

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ZIP code

63147

Very Hard

256 PPM

Nearest site
13.5 mi
Confidence
Moderate

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ZIP code

63155

Very Hard

255 PPM

Nearest site
16.1 mi
Confidence
Moderate

View full ZIP evidence →

Public water systems

Utilities associated with this city

St Louis City Pws

PWSID MO6010715

Surface water
System population served
304,709
Last reported
Jun 16, 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.

RecordSystemPeriodStatus
Lead and Copper RuleMO6010715Dec 30, 2025Unaddressed
LEAD AND COPPER RULE REVISIONSMO6010715Jul 2, 2025Unaddressed
SimazineMO6010715Oct 1, 2022Resolved
AtrazineMO6010715Oct 1, 2022Resolved
LASSOMO6010715Oct 1, 2022Resolved
AtrazineMO6010715Jul 1, 2022Resolved
LASSOMO6010715Jul 1, 2022Resolved
SimazineMO6010715Jul 1, 2022Resolved

Practical next steps

Move from index to evidence

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

Questions people ask

About water in St. Louis

Is the water hard?

The indexed city median is 255 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.