Home hazard report for 78667 — San Marcos, TX
ZIP 78667 is served by City of San Marcos (as listed by the state): 2 violations since 2016, latest lead result 1.6 ppb, PFAS 3 detected. Hays is in EPA radon zone 3.
Health-based violations since 2016: Tthm. All are listed as resolved.
90th-percentile lead in the latest round (Jan 2022). Lead comes mostly from household plumbing and service lines, so individual homes can be higher.
PFAS were detected, with PFOA and PFOS below 4.0 ppt (highest not detected).
Predicted average under 2 pCi/L — but any home can have high radon, so EPA still recommends a test.
No active Superfund site within 10 miles of the ZIP center.
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Where ZIP 78667 is
blue: utility service area · scroll or pinch to zoomDrinking water: City of San Marcos
Health-based violations
| Contaminant or rule | Health-based violations since 2016 |
|---|---|
| Tthm | 2 |
A health-based violation means a contaminant exceeded its legal limit (MCL) or a required treatment technique was not met, as reported by the state to EPA’s SDWIS. All are listed as resolved or archived; the latest began Oct 2025.
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 |
|---|---|---|---|
| PFBA | 11.4 ppt | 2 of 26 | — |
| PFPeA | 4.2 ppt | 6 of 26 | — |
| PFHxS | 3.4 ppt | 3 of 26 | — |
| PFDA | not detected | 0 of 26 | — |
| PFHxA | not detected | 0 of 26 | — |
| PFOA | not detected | 0 of 26 | 4 ppt MCL |
| HFPO-DA (GenX) | not detected | 0 of 26 | — |
| PFOS | not detected | 0 of 26 | 4 ppt MCL |
| PFBS | not detected | 0 of 26 | — |
| PFHpA | not detected | 0 of 26 | — |
| PFNA | not detected | 0 of 26 | — |
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 Hays
EPA radon zone 3 — low potential. Predicted average under 2 pCi/L — but any home can have high radon, so EPA still recommends a test.
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 78667
Who supplies drinking water to ZIP 78667?
City of San Marcos (EPA ID TX1050001), a surface water (rivers, lakes) system serving about 72,970 people, listed by the state as serving this ZIP code.
Is there lead in San Marcos, TX tap water?
The utility’s latest 90th-percentile lead result (Jan 2022) was 1.6 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 San Marcos, TX water have PFAS?
PFAS were detected, with PFOA and PFOS below 4.0 ppt (highest not detected).
Has the water system in 78667 had violations?
Health-based violations since 2016: Tthm. All are listed as resolved.
Are there Superfund sites near 78667?
No active Superfund site within 10 miles of the ZIP center.
Is radon a problem in Hays?
Hays is in EPA radon zone 3 (low potential). Predicted average under 2 pCi/L — but any home can have high radon, so EPA still recommends a test.