- EPA's UCMR 5 testing looked for 30 contaminants here and found 6.
- Lithium: found in 6 of 8 samples, average 10.7 µg/L, highest 20.7 µg/L (EPA UCMR 5 testing, Apr 2023–Oct 2023)
- PFOS (a PFAS): found in 4 of 8 samples, average 6.6 ppt, highest 22.3 ppt (EPA UCMR 5 testing, Apr 2023–Oct 2023) PFOA or PFOS averaged above 4.0 ppt in UCMR 5 testing
- PFHxS (a PFAS): found in 6 of 8 samples, average 3.5 ppt, highest 7.6 ppt (EPA UCMR 5 testing, Apr 2023–Oct 2023)
- PFBS (a PFAS): found in 4 of 8 samples, average 2.5 ppt, highest 9.4 ppt (EPA UCMR 5 testing, Apr 2023–Oct 2023)
- PFBA (a PFAS): found in 2 of 8 samples, average 2.2 ppt, highest 10 ppt (EPA UCMR 5 testing, Apr 2023–Oct 2023)
- PFOA (a PFAS): found in 2 of 8 samples, average 2 ppt, highest 8.4 ppt (EPA UCMR 5 testing, Apr 2023–Oct 2023)
- Lead, 90th percentile: 0 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, 2026–Dec 31, 2026). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
Public EPA test results
Can you drink Atascadero tap water? What EPA records show
EPA CA4010002 · serves San Luis Obispo County, CA · about 33,307 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
Atascadero Mutual Water CO (EPA CA4010002)
EPA data as of October 14, 2026. For Atascadero's main utility, Atascadero Mutual Water CO: We found no health-based violations in EPA's records for this system (CA4010002) since July 1, 2021, as of October 14, 2026. This water system averaged above 4.0 ppt for PFOA or PFOS in EPA's UCMR 5 testing.
What EPA records show for Atascadero Mutual Water CO, as of October 14, 2026
We found no health-based violations in EPA's records for this system (CA4010002) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Atascadero Mutual Water CO (SDWIS). Data as of October 14, 2026.
Lead, 90th percentile: 0 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, 2026–Dec 31, 2026). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
This water system averaged above 4.0 ppt for PFOA or PFOS in EPA's UCMR 5 testing.
EPA's UCMR 5 testing looked for 30 contaminants here and found 6.
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 Atascadero Mutual Water CO use chloramine?
We didn't find chloramine in Atascadero Mutual Water CO's EPA treatment records. That's not a complete list; your utility's annual water quality report says which disinfectant it uses.