Colusa County, CA
drinking water quality

22,074 residents · 29 public water systems · 7 ZIP codes

Worst PFAS result on federal record
No PFAS above the federal limit

EPA sampled 2 of 29 public water systems here, together serving about 11,985 people. Last sampled 9/11/2024.

Health-based violations

Separately from PFAS, EPA records 20 health-based violations across 1 of the county’s water systems since 2020, the most recent in 2024. They involved arsenic.

What this means

PFAS are industrial chemicals that EPA describes as breaking down only very slowly in the environment. In April 2024 EPA set the first enforceable national limits: 4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS, PFNA and GenX.

These figures are county-level and come from EPA’s sampling of public water systems. They describe the worst result found in the county, not what comes out of any particular tap — that depends on which system serves the address, and on the plumbing in the building. A private well is not covered by this programme at all.

Request a test of your own supply.

This is Colusa County's worst federal result, not a reading from your tap. Leave a number and a local water specialist will test it.

No obligation. Your details go to a local water specialist to arrange the test, and to no one else.

ZIP codes in Colusa County

95912 · 95932 · 95950 · 95955 · 95970 · 95979 · 95987

Readings are county-level, so every ZIP here shares the figure above. Search your ZIP on the map to see it in context.

Other California counties

Alameda CountyContra Costa CountyFresno CountyKern CountyLos Angeles CountyOrange CountyRiverside CountySacramento CountySan Bernardino CountySan Diego CountySanta Clara CountyVentura County

See every California county, ranked by what was found