Skip to content

City water profile

Oshkosh water quality

Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for Oshkosh, Wisconsin.

Median indexed hardness

243PPM

4 indexed ZIPs

Range 243–248.5 PPM

State comparison
45 PPM below
State hardness rank
#386 of 479
Matched utilities
2
Active health records
0

City summary

What the indexed records say

Oshkosh has 4 published ZIP profiles across Winnebago County. The indexed median is 243 PPM, compared with 288 PPM across Wisconsin.

Among the 479 Wisconsincities with an indexed median, Oshkosh ranks #386from highest to lowest. Across all 556 state ZIP profiles, available estimates run from 41.3to 467 PPM.

The 243–248.5 PPM range shows how much the available ZIP estimates vary within the city label. At least one estimate is marked low confidence, so observation distance and date deserve extra attention.

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
25.5 miles
Profiles with evidence
4/4

Confidence labels

High: 0Moderate: 2Low: 2

Observation window: Jan 11, 2016 to Jun 10, 2026.

ZIP directory

Water reports in Oshkosh

Open a ZIP for site-level provenance and measurements.

ZIP code

54901

Very Hard

243 PPM

Nearest site
25.5 mi
Confidence
Low

View full ZIP evidence →

ZIP code

54902

Very Hard

248.5 PPM

Nearest site
21 mi
Confidence
Moderate

View full ZIP evidence →

ZIP code

54904

Very Hard

243 PPM

Nearest site
20.4 mi
Confidence
Moderate

View full ZIP evidence →

ZIP code

54985

Very Hard

243 PPM

Nearest site
26.7 mi
Confidence
Low

View full ZIP evidence →

Public water systems

Utilities associated with this city

Oshkosh Waterworks

PWSID WI4710457

Surface water
System population served
63,000
Last reported
May 29, 2026

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

Algoma Tn Sanitary Dist 1

PWSID WI4711611

Groundwater
System population served
3,935
Last reported
May 29, 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
BromateWI4710457Jul 1, 2023Resolved

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 Oshkosh

Is the water hard?

The indexed city median is 243 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.