Public EPA test results
What EPA records show for Cal-Water Service Co.-Oroville
EPA CA0410005 · serves Butte County, CA · about 11,047 people (EPA SDWIS)
This report shows EPA's federal records for this water system: UCMR 5 testing, lead testing and violations. It isn't a test of the water at your tap, and it has no Water Score.
Public EPA test results
Cal-Water Service Co.-Oroville (EPA CA0410005)
What EPA records show for Cal-Water Service Co.-Oroville, as of October 14, 2026
We found no health-based violations in EPA's records for this system (CA0410005) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Cal-Water Service Co.-Oroville (SDWIS). Data as of October 14, 2026.
Lead, 90th percentile: 0.9 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2023–Dec 31, 2025). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
EPA's UCMR 5 testing looked for 30 contaminants here and found 2.
PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
Source: EPA records (SDWIS, UCMR 5). SDWIS: data as of Oct 14, 2026. EPA UCMR 5 data, samples through June 2026.
Your water bill names your utility.
Does Cal-Water Service Co.-Oroville use chloramine?
We didn't find chloramine in Cal-Water Service Co.-Oroville's EPA treatment records. That's not a complete list; your utility's annual water quality report says which disinfectant it uses.
What EPA records show for this system
Reported results in EPA records (data as of Oct 14–15, 2026)