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City water profile

Sonoma water quality

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

Median indexed hardness

181PPM

One indexed ZIP

Range 180.5–180.5 PPM

State comparison
8 PPM below
State hardness rank
#165 of 242
Matched utilities
2
Active health records
0

City summary

What the indexed records say

Sonoma has 1 published ZIP profile across Sonoma County. The indexed median is 181 PPM, compared with 189 PPM across California.

Among the 242 Californiacities with an indexed median, Sonoma ranks #165from highest to lowest. Across all 678 state ZIP profiles, available estimates run from 3.3to 728.5 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
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
1 miles
Profiles with evidence
1/1

Confidence labels

High: 0Moderate: 1Low: 0

Observation window: Feb 8, 2016 to Jul 31, 2023.

ZIP directory

Water reports in Sonoma

Open a ZIP for site-level provenance and measurements.

ZIP code

95476

Very Hard

180.5 PPM

Nearest site
1 mi
Confidence
Moderate

View full ZIP evidence →

Public water systems

Utilities associated with this city

Sonoma, City Of

PWSID CA4910012

Groundwater
System population served
11,725
Last reported
Jun 22, 2026

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

Eddy Drive

PWSID CA4901671

Groundwater
System population served
48
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
LEAD AND COPPER RULE REVISIONSCA4910012Jul 2, 2025Unaddressed
ArsenicCA4910012Apr 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 Sonoma

Is the water hard?

The indexed city median is 181 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.