Updated 2026-09-16

County water report

Butte County Water Quality

Name: Butte County Water Quality Data (2026)
Creator: PurityMap
License: https://creativecommons.org/licenses/by/4.0/

Butte County, California: one city report built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my system Open on the map

Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

Perfluorooctanesulfonic acid (PFOS)CAL-WATER SERVICE CO.-CHICO4.0 ng/L federal MCL (2024) · US EPA22.5 ng/L

CAL-WATER SERVICE CO.-CHICO22.5 ng/LSample date: 2023-09-18 to 2024-07-23

Perfluorohexanesulfonic acid (PFHxS)CAL-WATER SERVICE CO.-CHICO10 ng/L federal MCL (2024) · US EPA22.1 ng/L

CAL-WATER SERVICE CO.-CHICO22.1 ng/LSample date: 2023-09-18 to 2024-07-23

Perfluorooctanoic acid (PFOA)CAL-WATER SERVICE CO.-CHICO4.0 ng/L federal MCL (2024) · US EPA6.8 ng/L

CAL-WATER SERVICE CO.-CHICO6.8 ng/LSample date: 2023-09-18 to 2024-07-23

LithiumCAL-WATER SERVICE CO.-CHICO10 µg/L EPA health reference level (screening, not a legal limit) · US EPA11.7 µg/L

CAL-WATER SERVICE CO.-CHICO11.7 µg/LSample date: 2023-09-18 to 2024-07-23

Perfluorobutanesulfonic acid (PFBS)CAL-WATER SERVICE CO.-CHICO2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPA9.6 ng/L

CAL-WATER SERVICE CO.-CHICO9.6 ng/LSample date: 2023-09-18 to 2024-07-23

Perfluorohexanoic acid (PFHxA)CAL-WATER SERVICE CO.-CHICO400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLE6 ng/L

CAL-WATER SERVICE CO.-CHICO6 ng/LSample date: 2023-09-18 to 2024-07-23

Perfluoropentanoic acid (PFPeA)CAL-WATER SERVICE CO.-CHICONo federal or state limit; shown for transparency5.3 ng/L

CAL-WATER SERVICE CO.-CHICO5.3 ng/LSample date: 2023-09-18 to 2024-07-23

24 substances tested, none detected in this systemShow

Tested in this system: CAL-WATER SERVICE CO.-CHICO

11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
Lead (90th percentile)
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
Perfluoro-3-methoxypropanoic acid (PFMPA)
Perfluoro-4-methoxybutanoic acid (PFMBA)
Perfluorobutanoic acid (PFBA)
Perfluorodecanoic acid (PFDA)
Perfluorododecanoic acid (PFDoA)
Perfluoroheptanesulfonic acid (PFHpS)
Perfluoroheptanoic acid (PFHpA)
Perfluorononanoic acid (PFNA)
Perfluoropentanesulfonic acid (PFPeS)
Perfluorotetradecanoic acid (PFTA)
Perfluorotridecanoic acid (PFTrDA)
Perfluoroundecanoic acid (PFUnA)

1 city

Cities ranked by the records

1
ChicoCAL-WATER SERVICE CO.-CHICO
PFAS above limit
Open city report →

Showing 1 of 1 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.

PFAS in Butte County1 of 1 city reports a regulated PFAS above the federal limit

Chico22.5 ng/L

4.0 ng/L federal MCL · PFOS, ng/LPFAS in California

Lead

0of 1 city above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in California

Who supplies the county

Largest water systems

ChicoCAL-WATER SERVICE CO.-CHICO · CA0410002
110,473 served

Questions

Frequently asked

How does Butte County tap water compare across cities?

PurityMap ranks 1 city in Butte County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Chico's main water system: CAL-WATER SERVICE CO.-CHICO · PWSID CA0410002 · Purity Score 57 (Fair) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Butte County cities have PFAS above the federal limit?

1 city of 1 had at least one regulated PFAS (PFOA, PFOS or PFHxS) measured above the 2024 federal limit in EPA's UCMR 5 testing, including Chico (PFOS 22.5 ng/L). PFAS were detected at any level in 1.

Is there lead in Butte County tap water?

Utilities report lead as a 90th-percentile result from home taps. 0 of 1 Butte County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

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