Atascadero State Hospital Water System water quality
Atascadero, CA · serves 1,100 people (866 connections) · Groundwater · State · EPA ID CA4010832
Data: U.S. EPA · How we read the data · How we check it
Buys water from Atascadero Mutual Water Company. Treated water bought from another system can carry that system's contaminants.
Summary
PFAS above the 2024 federal limits. Systems have until 2029 to meet the PFAS limits.
Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility ever issues a boil-water or do-not-drink notice, follow it.
- PFAS
- Above limitPFOS, PFHxS, the PFAS Hazard Index above the federal limit in EPA's 2023–2025 testing (PFOS 18.6 ppt vs a limit of 4 ppt, PFHxS 19.2 ppt vs a limit of 10 ppt, where ppt = parts per trillion).
- Lead
- Below action level4.7 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period ending Jun 2026. Your home's pipes can make yours higher.
- Violations
- None health-basedNo health-based violations since 2016.
- Pregnant, or mixing baby formula with tap water? Babies drink more water for their size, so PFAS exposure matters more for them. Consider bottled water or a filter certified for PFAS for formula, and ask your doctor. Health effects.
- To lower your PFAS exposure now, a home filter certified for PFAS reduction works (reverse osmosis, or activated carbon certified to NSF/ANSI 53 or 58). Filters for these results.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read Atascadero State Hospital Water System's annual water quality report (Consumer Confidence Report). It lists every regulated contaminant tested and is usually on the utility's website or mailed with your bill, and you can also request it at (805) 468-2249. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 1 entry point tested Feb 2023 to Aug 2023. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA Not detected Limit 4 ppt | – |
| PFOS Above limit Limit 4 ppt | 18.6 ppt 4.66× the limit |
| PFHxS Above limit Limit 10 ppt | 19.2 ppt 1.92× the limit |
| PFNA Not detected Limit 10 ppt | – |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Above limit Limit 1 | 1.92 |
| PFBS Detected, below limit Guideline 2,000 ppt | 4.55 ppt |
| PFBA Not detected Guideline 6,000 ppt | – |
| PFHxA Detected, below limit Guideline 3,000 ppt | 1.8 ppt |
| PFPeS Detected, no limit | 3.05 ppt |
For context: the PFOS average is higher than at 95% of the California systems EPA tested and the PFHxS average is higher than at 99% of the California systems EPA tested.
29 PFAS tested, 5 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Not detected in 2 samples (reporting limit 9 ppb). About lithium.
Lead and copper
Latest 90th percentile: 4.7 ppb lead (Jan 2026 – Jun 2026). Below action level
Highest since 2016: 7 ppb (Dec 2024).
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2026 – Jun 2026 | 4.7 ppb |
| Jul 2025 – Dec 2025 | 4.5 ppb |
| Jan 2025 – Jun 2025 | 6.1 ppb |
Earlier results (9)
| Jan 2022 – Dec 2024 | 7 ppb |
| Jan 2019 – Dec 2021 | 0 ppb |
| Jan 2016 – Dec 2018 | 2.2 ppb |
| Jan 2013 – Dec 2015 | 0.9 ppb |
| Jan 2010 – Dec 2012 | 6.2 ppb |
| Jan 2009 – Dec 2009 | 4 ppb |
| Jan 2008 – Dec 2008 | 24 ppb |
| Jan 2002 – Dec 2004 | 5 ppb |
| Jan 2002 – Dec 2002 | 24 ppb |
Copper 90th percentile: 1.58 ppm (Jun 2026), action level 1,300 ppb.
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Where it serves
ZIP codes the system reported serving: 93423
Questions
Is Atascadero State Hospital Water System water safe to drink?
Atascadero State Hospital Water System has no health-based violations since 2016. EPA testing found PFAS above the 2024 federal limits, which systems must meet by 2029. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does Atascadero State Hospital Water System water have PFAS?
Yes. EPA's 2023–2025 testing of Atascadero State Hospital Water System found 5 PFAS at least once. The highest entry-point averages were above the federal limit for PFOS and PFHxS: PFOS 18.6 ppt, PFHxS 19.2 ppt (limit 4 ppt for PFOA and PFOS, 10 ppt for the others).
What is the lead level in Atascadero State Hospital Water System water?
The most recent 90th-percentile lead result for Atascadero State Hospital Water System is 4.7 ppb, for the period ending Jun 2026. The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for CA4010832: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID CA4010832).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask Atascadero State Hospital Water System at (805) 468-2249, or see EPA's guide to finding it.
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.