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City water profile

San Marcos water quality

Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for San Marcos, Texas.

Median indexed hardness

163PPM

One indexed ZIP

Range 162.5–162.5 PPM

State comparison
52 PPM above
State hardness rank
#258 of 523
Matched utilities
1
Active health records
0

City summary

What the indexed records say

San Marcos has 1 published ZIP profile across Hays County. The indexed median is 163 PPM, compared with 111 PPM across Texas.

Among the 523 Texascities with an indexed median, San Marcos ranks #258from highest to lowest. Across all 1,026 state ZIP profiles, available estimates run from 5.4to 500.5 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.

Hardness distribution

How local ZIP estimates compare

Soft0 ZIPs
Moderately hard0 ZIPs
Hard1 ZIP
Very hard0 ZIPs

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
14 miles
Profiles with evidence
1/1

Confidence labels

High: 0Moderate: 1Low: 0

Observation window: Jun 2, 2016 to Jun 20, 2026.

ZIP directory

Water reports in San Marcos

Open a ZIP for site-level provenance and measurements.

ZIP code

78666

Hard

162.5 PPM

Nearest site
14 mi
Confidence
Moderate

View full ZIP evidence →

Public water systems

Utilities associated with this city

City Of San Marcos

PWSID TX1050001

Surface water
System population served
72,970
Last reported
Jun 26, 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
TTHMTX1050001Oct 1, 2025Resolved · health-based
ChloriteTX1050001Feb 1, 2021Resolved

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 San Marcos

Is the water hard?

The indexed city median is 163 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.