Home hazard report for 93423 — Atascadero, CA
ZIP 93423 is served by Atascadero State Hospital (as listed by the state): no health-based violations since 2016, latest lead result 4.7 ppb, PFAS 33 ppt. San Luis Obispo is in EPA radon zone 2.
No health-based violations reported since 2016.
90th-percentile lead in the latest round (Jan 2026). Lead comes mostly from household plumbing and service lines, so individual homes can be higher.
Highest PFOA or PFOS result in EPA’s 2023–2025 testing was at or above 4.0 ppt, EPA’s 2024 maximum contaminant level for each. 4 PFAS compounds detected.
Predicted average indoor radon between 2 and 4 pCi/L. Test your home; many homes here exceed 4 pCi/L.
No active Superfund site within 10 miles of the ZIP center.
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Where ZIP 93423 is
blue: utility service area · scroll or pinch to zoomDrinking water: Atascadero State Hospital
Health-based violations
No health-based violations reported since 2016.
Lead
90th-percentile lead per sampling round (90% of the homes sampled were at or below this level). Black line: EPA’s 15 ppb action level; under the Lead and Copper Rule Improvements the action level becomes 10 ppb from 2027.
PFAS (“forever chemicals”)
| Compound | Highest result | Samples with detection | EPA limit |
|---|---|---|---|
| PFHxS | 34 ppt | 2 of 2 | — |
| PFOS | 33 ppt | 2 of 2 | 4 ppt MCL |
| PFBS | 5.5 ppt | 2 of 2 | — |
| PFHxA | 3.6 ppt | 1 of 2 | — |
| PFOA | not detected | 0 of 2 | 4 ppt MCL |
| PFPeA | not detected | 0 of 2 | — |
| PFBA | not detected | 0 of 2 | — |
| HFPO-DA (GenX) | not detected | 0 of 2 | — |
| PFNA | not detected | 0 of 2 | — |
| PFDA | not detected | 0 of 2 | — |
| PFHpA | not detected | 0 of 2 | — |
EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), samples 2023–2025; ppt = parts per trillion (ng/L). The 4.0 ppt maximum contaminant levels for PFOA and PFOS were set by EPA in 2024; water systems have until the end of the decade to comply.
Radon in San Luis Obispo
EPA radon zone 2 — moderate potential. Predicted average indoor radon between 2 and 4 pCi/L. Test your home; many homes here exceed 4 pCi/L.
Radon is a colorless, odorless radioactive gas from soil and rock, and the leading cause of lung cancer among non-smokers. EPA recommends fixing a home at 4 pCi/L or above and considering it from 2 pCi/L. A short-term test kit costs about $15–30. How radon zones work →
Superfund sites nearby
No site on EPA’s Superfund National Priorities List lies within 10 miles of the center of this ZIP code.
EPA Superfund National Priorities List (NPL): the country’s most serious known hazardous-waste sites, each with an EPA cleanup record (linked). Distance is measured from the ZIP center to the site’s reference point; being near a site does not by itself mean exposure — EPA site pages describe what was found and how it is being cleaned up.
What this is — and isn’t. These are records your water utility and state reported to the EPA, and the EPA’s radon map for your county. They describe the system and the area, not the water from your own tap or the air in your home. For that, read your utility’s annual Consumer Confidence Report and test: lead and radon tests are inexpensive.
Questions about 93423
Who supplies drinking water to ZIP 93423?
Atascadero State Hospital (EPA ID CA4010832), a groundwater (wells) system serving about 1,100 people, listed by the state as serving this ZIP code.
Is there lead in Atascadero, CA tap water?
The utility’s latest 90th-percentile lead result (Jan 2026) was 4.7 ppb; EPA’s action level is 15 ppb, falling to 10 ppb from 2027. Lead mostly comes from service lines and home plumbing, so the only way to know your tap is to test it.
Does Atascadero, CA water have PFAS?
Highest PFOA or PFOS result in EPA’s 2023–2025 testing was at or above 4.0 ppt, EPA’s 2024 maximum contaminant level for each. 4 PFAS compounds detected.
Has the water system in 93423 had violations?
No health-based violations reported since 2016.
Are there Superfund sites near 93423?
No active Superfund site within 10 miles of the ZIP center.
Is radon a problem in San Luis Obispo?
San Luis Obispo is in EPA radon zone 2 (moderate potential). Predicted average indoor radon between 2 and 4 pCi/L. Test your home; many homes here exceed 4 pCi/L.