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City water profile

Hollis water quality

Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for Hollis, Oklahoma.

Median indexed hardness

190PPM

One indexed ZIP

Range 189.5–189.5 PPM

State comparison
36 PPM below
State hardness rank
#77 of 108
Matched utilities
1
Active health records
0

City summary

What the indexed records say

Hollis has 1 published ZIP profile across Harmon County. The indexed median is 190 PPM, compared with 226 PPM across Oklahoma.

Among the 108 Oklahomacities with an indexed median, Hollis ranks #77from highest to lowest. Across all 148 state ZIP profiles, available estimates run from 7to 610 PPM.

Because only one ZIP is represented, the city median and range are the same local estimate. It should not be read as multiple independent samples across the community. 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 hard1 ZIP

1 of 1 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.

Evidence quality

Distance, dates, and confidence

Median nearest distance
52.9 miles
Profiles with evidence
1/1

Confidence labels

High: 0Moderate: 0Low: 1

Observation window: Jun 15, 2016 to May 10, 2021.

ZIP directory

Water reports in Hollis

Open a ZIP for site-level provenance and measurements.

ZIP code

73550

Very Hard

189.5 PPM

Nearest site
52.9 mi
Confidence
Low

View full ZIP evidence →

Public water systems

Utilities associated with this city

Hollis

PWSID OK2002901

Groundwater
System population served
2,264
Last reported
May 13, 2026

A municipal system, in-state city, and served county all agree with this Census 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 RuleOK2002901Oct 1, 2024Unaddressed
Nitrate-NitriteOK2002901Jul 1, 2024Resolved · health-based
Total Haloacetic Acids (HAA5)OK2002901Oct 1, 2022Resolved
TTHMOK2002901Oct 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 Hollis

Is the water hard?

The indexed city median is 190 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.