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City water profile

San Jose water quality

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

Median indexed hardness

271PPM

31 indexed ZIPs

Range 257–282.5 PPM

State comparison
82 PPM above
State hardness rank
#38 of 242
Matched utilities
4
Active health records
0

City summary

What the indexed records say

San Jose has 31 published ZIP profiles across Santa Clara County. The indexed median is 271 PPM, compared with 189 PPM across California.

Among the 242 Californiacities with an indexed median, San Jose ranks #38from highest to lowest. Across all 678 state ZIP profiles, available estimates run from 3.3to 728.5 PPM.

The 257–282.5 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 hard31 ZIPs

31 of 31 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.

Evidence quality

Distance, dates, and confidence

Median nearest distance
2.8 miles
Profiles with evidence
31/31

Confidence labels

High: 0Moderate: 31Low: 0

Observation window: Jan 13, 2016 to Jun 3, 2026.

ZIP directory

Water reports in San Jose

Open a ZIP for site-level provenance and measurements.

ZIP code

95002

Very Hard

273 PPM

Nearest site
6.2 mi
Confidence
Moderate

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ZIP code

95013

Very Hard

272 PPM

Nearest site
4.6 mi
Confidence
Moderate

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ZIP code

95037

Very Hard

275 PPM

Nearest site
4.9 mi
Confidence
Moderate

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ZIP code

95110

Very Hard

264 PPM

Nearest site
2.3 mi
Confidence
Moderate

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ZIP code

95111

Very Hard

272 PPM

Nearest site
2.2 mi
Confidence
Moderate

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ZIP code

95112

Very Hard

264 PPM

Nearest site
2.8 mi
Confidence
Moderate

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ZIP code

95113

Very Hard

264 PPM

Nearest site
2.1 mi
Confidence
Moderate

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ZIP code

95116

Very Hard

264 PPM

Nearest site
3.6 mi
Confidence
Moderate

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ZIP code

95117

Very Hard

264 PPM

Nearest site
2 mi
Confidence
Moderate

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ZIP code

95118

Very Hard

271 PPM

Nearest site
3.4 mi
Confidence
Moderate

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ZIP code

95119

Very Hard

271 PPM

Nearest site
2.6 mi
Confidence
Moderate

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ZIP code

95120

Very Hard

272 PPM

Nearest site
4.8 mi
Confidence
Moderate

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ZIP code

95121

Very Hard

272 PPM

Nearest site
2.9 mi
Confidence
Moderate

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ZIP code

95122

Very Hard

257 PPM

Nearest site
3.1 mi
Confidence
Moderate

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ZIP code

95123

Very Hard

271 PPM

Nearest site
2.5 mi
Confidence
Moderate

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ZIP code

95124

Very Hard

272 PPM

Nearest site
2.6 mi
Confidence
Moderate

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ZIP code

95125

Very Hard

264 PPM

Nearest site
0.9 mi
Confidence
Moderate

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ZIP code

95126

Very Hard

264 PPM

Nearest site
2.4 mi
Confidence
Moderate

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ZIP code

95127

Very Hard

257 PPM

Nearest site
6.3 mi
Confidence
Moderate

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ZIP code

95128

Very Hard

264 PPM

Nearest site
1.5 mi
Confidence
Moderate

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ZIP code

95129

Very Hard

271 PPM

Nearest site
2.5 mi
Confidence
Moderate

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ZIP code

95130

Very Hard

264 PPM

Nearest site
1.7 mi
Confidence
Moderate

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ZIP code

95131

Very Hard

271 PPM

Nearest site
0.6 mi
Confidence
Moderate

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ZIP code

95132

Very Hard

257 PPM

Nearest site
3.2 mi
Confidence
Moderate

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ZIP code

95133

Very Hard

264 PPM

Nearest site
2.7 mi
Confidence
Moderate

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ZIP code

95134

Very Hard

272 PPM

Nearest site
3.8 mi
Confidence
Moderate

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ZIP code

95135

Very Hard

282.5 PPM

Nearest site
10.2 mi
Confidence
Moderate

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ZIP code

95136

Very Hard

272 PPM

Nearest site
2.8 mi
Confidence
Moderate

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ZIP code

95138

Very Hard

271 PPM

Nearest site
2.9 mi
Confidence
Moderate

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ZIP code

95139

Very Hard

272 PPM

Nearest site
3.2 mi
Confidence
Moderate

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ZIP code

95148

Very Hard

257 PPM

Nearest site
4.8 mi
Confidence
Moderate

View full ZIP evidence →

Public water systems

Utilities associated with this city

San Jose Water

PWSID CA4310011

Surface water
System population served
1,039,920
Last reported
Jun 22, 2026

A municipal system, in-state city, and served county all agree with this Census ZCTA.

City Of San Jose - Evg/edv/coy

PWSID CA4310020

Surface water
System population served
101,265
Last reported
Jun 22, 2026

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

City Of San Jose - Nsj/alviso

PWSID CA4310019

Surface water
System population served
45,559
Last reported
Jun 22, 2026

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

Cwsc King City

PWSID CA2710009

Groundwater
System population served
16,334
Last reported
Jun 22, 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
Surface Water Treatment RuleCA4310011Jun 1, 2023Resolved · health-based

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 Jose

Is the water hard?

The indexed city median is 271 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.