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City of Sonoma water quality report, rewritten

Serves
11,725
Connections
4,343
Water source
Groundwater
Based in
Sonoma, CA
County
Sonoma
Owner
Local government
The ZIP code it serves

95476

PWSID CA49100122026 edition · EPA data

Read this first

  • PFOA (above the health goal) was found in two of 12 samples, highest 6.2 ppt. Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.
  • Lithium (above EPA’s health benchmark) was found in 10 of 12 samples, highest 40 ppb. Above EPA’s health reference level of 10 ppb, a screening level rather than an enforceable limit.

No health-based violations on file since 2016. EPA lists 5 monitoring or reporting violations, which are paperwork and testing lapses rather than water quality findings.

What handles it

What was found

Highlighted: above the health goal, or EPA’s health benchmark where there is no goal. Circled: above the legal limit in at least one sample, or the action level. Every scale puts that line at its middle.

PFOA (above the health goal)

Comes from the source

6.2 (above the legal limit in at least one sample)ppt

Highest of 12 samples; found in two

Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.

What handles it

  • NSF/ANSI 53Look for: PFOA ReductionSame claim, other certifiers’ wording: Total PFAS Reduction; Perfluorooctanoic Acid (PFOA)
  • NSF/ANSI 58Look for: Perfluorooctanoic Acid (PFOA)

NSF’s PFAS claims are tested to below 20 ppt. EPA’s limit is 4.0 ppt, and EPA says no certification yet shows a filter reaching its levels.

EPA UCMR 5, samples taken from July 19, 2023 to Jan. 16, 2024. Each blue tick is one sample where it was found.

40ppb

Highest of 12 samples; found in 10

Above EPA’s health reference level of 10 ppb, a screening level rather than an enforceable limit.

What handles it

No certification claim covers this compound yet.

EPA UCMR 5, samples taken from July 19, 2023 to Jan. 16, 2024. Each blue tick is one sample where it was found.

Also found, with no federal limit

EPA measured these PFAS to learn how often they occur. None has a legal limit or a health goal yet.

CompoundHighest sampleFound inCertification claim
PFHxA6.1 ppt2 of 12None covers it

Tested and not found

Below EPA’s minimum reporting level in every sample taken from July 19, 2023 to Jan. 16, 2024. Not found means not measured above that level, which is not the same as zero.

All 28 compounds tested and not found
  • 11Cl-PF3OUdS
  • 4:2 FTS
  • 6:2 FTS
  • 8:2 FTS
  • 9Cl-PF3ONS
  • ADONA
  • HFPO-DA (GenX)
  • Lead
  • NEtFOSAA
  • NFDHA
  • NMeFOSAA
  • PFBA
  • PFBS
  • PFDA
  • PFDoA
  • PFEESA
  • PFHpA
  • PFHpS
  • PFHxS
  • PFMBA
  • PFMPA
  • PFNA
  • PFOS
  • PFPeA
  • PFPeS
  • PFTA
  • PFTrDA
  • PFUnA

Violations since 2016

No health-based violations on file with EPA since 2016. There are 5 monitoring or reporting violations: a sample missed, late or not reported.

What handles it

A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”

At the tap, or for the whole house?

These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. How whole-house systems compare.

Compare five-year costs

Filters with those claims on a certifier’s listing

TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

What this report cannot tell you

  • Levels of everything else. Federal bulk data carries results for PFAS, lithium, lead and copper, and violations for the rest. Nitrate, arsenic, disinfection byproducts and other levels are in City of Sonoma’s own annual report, which it must send you every year.
  • Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
  • Anything after the latest data. SDWIS data is from 2026 Q2; UCMR 5 samples are from July 19, 2023 to Jan. 16, 2024.

What to do next

  1. Read up on the 2 marked results

    What each one does to health, where it comes from, and the certification claim that addresses it.

    Start with PFOA

  2. Get the utility’s own report

    City of Sonoma must send you a water quality report every year. It lists nitrate, arsenic and byproduct levels this page cannot.

    How to read it

  3. Test your own tap for lead

    Your service line, solder and fixtures decide the lead at your faucet, not the utility’s average.

    Lead in your water: what to do

  4. Compare certified filters

    What the filters certified for these results cost over five years, cartridges included.

    Compare five-year costs

Other California utilities

All California utilities

Sources