Cal-Water Service Co.-Chico Water Quality (California) – 2025 Report Results

We read 23 results from Cal-Water Service Co.-Chico’s 2025 water quality report. No results over a legal limit; 7 above a health goal or guideline.

Serves about 114,925 people · Water system ID CA0410002 · Read the district’s 2025 report (opens in a new tab)

Open this district in the water lookupCompare with your own test results, see the district map and get matched filters.

Results from the 2025 report

Each number is copied from the district’s report and links to the page it’s printed on. Where the report lists several plants, wells or purchased water, the highest is shown.

Contaminant	Result	Health goal	Legal limit	What it means
Chromium-6average · range 0.42 to 9.1 · Groundwater wells · 2025 report, page 13	2.2 ppb	0.02 ppb	10 ppb	Above the health goal110x the health goal
Gross alpha (radioactivity)highest measured · range ND to 5.2 · Groundwater wells · 2025 report, page 13	5.2 pCi/L	0 pCi/L	15 pCi/L	Above the health goalThe health goal is zero
PFHxS (a PFAS)highest measured · range ND to 26 · Groundwater wells · 2025 report, page 14	26 ppt	None set	10 ppt from 2029	Above the federal limit that takes effect in 20292.6x the 10 ppt federal limit that takes effect in 2029Not a violation yet: EPA's 10 ppt limit is final, but water systems don't have to meet it until 2029.
PFOA (a PFAS)highest measured · range ND to 7.8 · Groundwater wells · 2025 report, page 14	7.8 ppt	0.007 ppt	4 ppt from 2029	Above the federal limit that takes effect in 20292x the 4 ppt federal limit that takes effect in 2029Not a violation yet: EPA's 4 ppt limit is final, but water systems don't have to meet it until 2029.
PFOS (a PFAS)highest measured · range ND to 31 · Groundwater wells · 2025 report, page 14	31 ppt	1 ppt	4 ppt from 2029	Above the federal limit that takes effect in 20297.8x the 4 ppt federal limit that takes effect in 2029Not a violation yet: EPA's 4 ppt limit is final, but water systems don't have to meet it until 2029.
Radium-228highest measured · range ND to 2.6 · Groundwater wells · 2025 report, page 13	2.6 pCi/L	0.02 pCi/L	5 pCi/L	Above the health goal137x the health goal
Tetrachloroethylene (PCE)highest measured · range ND to 2.9 · Groundwater wells · 2025 report, page 13	2.9 ppb	0.06 ppb	5 ppb	Above the health goal48x the health goal
Chlorideaverage · range 2 to 56 · Groundwater wells · 2025 report, page 14	11 ppm	—	250 ppm guideline	Within the guideline
Chlorineaverage · range ND to 1.1 · Distribution system · 2025 report, page 14	0.6 ppm	None set	4 ppm	Below the legal limit
cis-1,2-Dichloroethylenehighest measured · range ND to 1.1 · Groundwater wells · 2025 report, page 13	1.1 ppb	70 ppb	70 ppb	Below the health goal
Copper90th percentile of 50 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 13	0.18 ppm	0.3 ppm	1.3 ppm (action level)	Below the health goal
Disinfection byproducts (TTHM)highest measured · range ND to 1.2 · Distribution system · 2025 report, page 13	1.2 ppb	None set	80 ppb	Below the legal limit
E. colias reported · Distribution system · 2025 report, page 13	Not detected	0 positive samples	0 positive samples	Not detected
Ironaverage · range ND to 0.37 · printed as ND ppb · Groundwater wells · 2025 report, page 14	Not detected	—	0.3 ppm guideline	Not detected
Lead90th percentile of 50 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 13	Not detected	0.2 ppb	15 ppb (action level)	Not detected
Nitrate (as N)average · range ND to 5.6 · Groundwater wells · 2025 report, page 13	1.7 ppm	10 ppm	10 ppm	Below the health goal
Sulfateaverage · range 1.4 to 18 · Groundwater wells · 2025 report, page 14	6.2 ppm	—	250 ppm guideline	Within the guideline
Total dissolved solidsaverage · range 160 to 440 · Groundwater wells · 2025 report, page 14	222 ppm	—	500 ppm guideline	Within the guideline
Turbidity (cloudiness)average · range ND to 2.1 · Groundwater wells · 2025 report, page 14	0.14 NTU	None set	1 NTU	Below the legal limit
Hardnessaverage · range 4.68 to 18.8 · Groundwater wells · 2025 report, page 15	7.25 gpg (124 ppm)	—	—	Hard
PFBS (a PFAS)average · range ND to 6.6 · Groundwater wells · 2025 report, page 14	0.72 ppt	None set	None	No health limit
Sodiumaverage · range 7.5 to 39 · Groundwater wells · 2025 report, page 15	14 ppm	None set	None	No health limit
Vanadiumaverage · range ND to 29 · Groundwater wells · 2025 report, page 14	14 ppb	None set	None	No health limit

Utility results describe the whole system, measured where water enters the pipes, not your tap. Your home’s plumbing can add lead or copper.

EPA testing for PFAS and lithium

EPA’s own nationwide testing (UCMR 5) found these in Cal-Water Service Co.-Chico’s water between Sep 2023 and Jul 2024. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.

PFOA6.8 pptFound in 2 of 74 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
PFOS22.5 pptFound in 15 of 74 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
PFHxS22.1 pptFound in 19 of 74 samples · highest resultNo federal limit in force for this one
PFBS9.6 pptFound in 6 of 74 samples · highest resultNo federal limit in force for this one
Lithium11.7 ppbFound in 3 of 74 samples · highest resultAbove EPA’s health reference level of 10 ppb (a guide, not a legal limit)

Source: EPA UCMR 5 occurrence data. The highest single result is shown; one high sample doesn’t mean every glass is that high.

What you can do

Nothing here is an emergency notice: if the district has a violation, it must tell customers directly. If you’d like to lower these at your tap, these are the treatments that remove them, and the catalog shows the models certified for each. Ranking is by certified removal; commissions never change the order.