City of Atwater
PWSID CA2410001 - Atwater
PFAS was measured above a final federal limit in this system.
The highest result was PFHxS at 59 ng/L, against a federal limit of 10 ng/L. A system over the limit has a legal obligation to act by 2031; it does not mean the water is unsafe to drink today, and it does not describe what reaches one specific tap.
29,479
people served
8,502
service connections
groundwater
primary source
480
sample results
Every compound detected
Highest single result per compound, in nanograms per litre (the same unit as parts per trillion). EPA proposed in May 2026 to rescind the limits marked as withdrawn, so those results are reported without a comparison.
| Compound | Highest result | Federal limit | Reading |
|---|---|---|---|
| PFHxS | 59 ng/L | withdrawn | no current limit |
| PFOS | 45 ng/L | 4 ng/L | above limit |
| PFOA | 33 ng/L | 4 ng/L | above limit |
| PFPeA | 27 ng/L | none | below limit |
| PFHxA | 25 ng/L | none | below limit |
| 6:2 FTS | 13 ng/L | none | below limit |
| PFHpA | 12 ng/L | none | below limit |
| PFBA | 11 ng/L | none | below limit |
| PFPeS | 8.2 ng/L | none | below limit |
| PFBS | 7.8 ng/L | none | below limit |
Counties served
What this does not tell you
These are entry-point results for the system, not one tap. Water mixes between sources, sits in mains and passes through household plumbing. A certified lab test of your own tap is the only thing that answers what you drink, and it is the only route at all for a private well.
How to test your tap waterIf you want to treat it
Reverse osmosis and properly specified activated carbon remove most PFAS at the tap. Certification to NSF/ANSI 53 or 58 with an explicit PFOA and PFOS claim is what separates a PFAS filter from a taste filter.
Which filters actually workSource: EPA Fifth Unregulated Contaminant Monitoring Rule occurrence data, with system detail from EPA SDWIS. Umwelt reports these results as published. Methodology and sources