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City of Merced water quality report, rewritten

Serves
93,692
Connections
24,363
Water source
Groundwater
Based in
Merced, CA
County
Merced
Owner
Local government
The 3 ZIP codes it serves

95340, 95341, 95348

PWSID CA2410009 · EPA data

Read this first

  • PFOS (above the health goal) was found in four of 42 samples, highest 8.9 ppt. Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.
  • PFOA (above the health goal) was found in three of 42 samples, highest 6.1 ppt. Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.
  • PFHxS (above the health goal) was found in seven of 42 samples, highest 15 ppt. Above the 10 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.

No health-based violations on file since 2016.

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.

PFAS and lithium: EPA UCMR 5, samples taken from July 13, 2023 to Sept. 19, 2024. Each blue tick on a scale is one sample where it was found.

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.

PFOS (above the health goal)

Comes from the source

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

Highest of 42 samples; found in four

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

PFOA (above the health goal)

Comes from the source

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

Highest of 42 samples; found in three

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

PFHxS (above the health goal)

Comes from the source

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

Highest of 42 samples; found in seven

Above the 10 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.

What handles it

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
PFHxA4.8 ppt4 of 42None covers it

Tested and not found

Below EPA’s minimum reporting level in every sample taken from July 13, 2023 to Sept. 19, 2024. Not found means not measured above that level, which is not the same as zero.

All 27 compounds tested and not found
  • 11Cl-PF3OUdS
  • 4:2 FTS
  • 6:2 FTS
  • 8:2 FTS
  • 9Cl-PF3ONS
  • ADONA
  • HFPO-DA (GenX)
  • Lead
  • Lithium
  • NEtFOSAA
  • NFDHA
  • NMeFOSAA
  • PFBA
  • PFBS
  • PFDA
  • PFDoA
  • PFEESA
  • PFHpA
  • PFHpS
  • PFMBA
  • PFMPA
  • PFNA
  • PFPeA
  • PFPeS
  • PFTA
  • PFTrDA
  • PFUnA

Violations since 2016

No health-based violations on file with EPA since 2016.

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.”

  • NSF/ANSI 53

    Claims: PFOS Reduction, PFOA Reduction, Total PFAS Reduction

    Other certifiers’ wording: Perfluorooctane Sulfonate (PFOS); Perfluorooctanoic Acid (PFOA); Perfluorohexane Sulfonic Acid (PFHxS)

    For: PFOS, PFOA, PFHxS

  • NSF/ANSI 58

    Claims: Perfluorooctane Sulfonate (PFOS), Perfluorooctanoic Acid (PFOA)

    For: PFOS, PFOA

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 Merced’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 13, 2023 to Sept. 19, 2024.

Other California utilities

All California utilities

Sources

What to do next

  • Read up on the 3 marked results

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

    Start with PFOS

  • Get the utility’s own report

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

    How to read it

  • 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

  • Compare certified filters

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

    Compare five-year costs