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City water profile

San Luis water quality

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

Median indexed hardness

449PPM

3 indexed ZIPs

Range 402–450 PPM

State comparison
208 PPM above
State hardness rank
#7 of 133
Matched utilities
1
Active health records
1

City summary

What the indexed records say

San Luis has 3 published ZIP profiles across Yuma County. The indexed median is 449 PPM, compared with 241 PPM across Arizona.

Among the 133 Arizonacities with an indexed median, San Luis ranks #7from highest to lowest. Across all 285 state ZIP profiles, available estimates run from 66.4to 1250 PPM.

The 402–450 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 hard3 ZIPs

3 of 3 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.

Evidence quality

Distance, dates, and confidence

Median nearest distance
14.8 miles
Profiles with evidence
3/3

Confidence labels

High: 0Moderate: 3Low: 0

Observation window: Mar 7, 2016 to Apr 9, 2026.

ZIP directory

Water reports in San Luis

Open a ZIP for site-level provenance and measurements.

ZIP code

85336

Very Hard

402 PPM

Nearest site
14.8 mi
Confidence
Moderate

View full ZIP evidence →

ZIP code

85349

Very Hard

450 PPM

Nearest site
17.4 mi
Confidence
Moderate

View full ZIP evidence →

ZIP code

85350

Very Hard

449 PPM

Nearest site
11.3 mi
Confidence
Moderate

View full ZIP evidence →

Public water systems

Utilities associated with this city

San Luis City Of

PWSID AZ0414005

Groundwater
System population served
39,705
Last reported
May 14, 2026

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

Compliance history

What EPA records show

1 unique active health-based record appears among associated systems. This does not mean every contaminant was tested at every tap.

RecordSystemPeriodStatus
Lead and Copper RuleAZ0414005Oct 1, 2024Resolved
Groundwater RuleAZ0414005Jun 6, 2024Resolved · health-based
Revised Total Coliform RuleAZ0414005Feb 1, 2024Resolved
Lead and Copper RuleAZ0414005Sep 28, 2021Resolved
Revised Total Coliform RuleAZ0414005Sep 15, 2021Unaddressed · health-based
TTHMAZ0414005Sep 8, 2021Resolved
E. COLIAZ0414005Sep 1, 2021Resolved
Groundwater RuleAZ0414005Aug 5, 2021Resolved · health-based
Revised Total Coliform RuleAZ0414005Aug 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 Luis

Is the water hard?

The indexed city median is 449 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.