Arsenic in Thermal, CA Drinking Water
Arsenic data for Thermal, California · 17,909 residents · 1 ZIP code
Across Thermal, California, federal monitoring data has captured Arsenic in water samples at detectable concentrations in the most recent available reporting cycle.
Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-04-05
Arsenic in Thermal Tap Water
Thermal, California has 3 EPA violations related to arsenic in drinking water.
This analysis covers 17,909 residents across 1 ZIP code in Thermal.
Thermal's overall water quality grade is C (66/100).
Is Arsenic in Thermal Water Safe?
If you live in an affected ZIP code, consider installing a reverse osmosis filter certified under NSF 53 / NSF 58 and testing your water independently.
EPA Violations for Arsenic in Thermal
| Date | Violation Type | Status | ZIP Code |
|---|---|---|---|
| 2022-10-01 | Arsenic (Known) | Known | 92274 |
| 2022-07-01 | Arsenic (Known) | Known | 92274 |
| 2022-04-01 | Arsenic (Known) | Known | 92274 |
Health Effects of Arsenic
- Increased risk of skin, bladder, lung, and kidney cancer
- Cardiovascular disease and type 2 diabetes
- Skin changes (darkening, thickening, lesions)
- Developmental effects in children exposed in utero
Health risk severity: High. Governed by the Arsenic Rule (2006).
How Arsenic Gets Into Drinking Water
- Natural deposits in rock and soil (especially in western U.S.)
- Runoff from orchards and glass/electronics production
- Historical use of arsenic-based pesticides
- Well water in areas with arsenic-rich geology
What to Do About Arsenic in Thermal Water
- Install a reverse osmosis (RO) system certified under NSF 58
- Adsorptive media filters (iron-based) can also reduce arsenic
- Have well water tested if on a private supply
- Boiling water does NOT remove arsenic — it concentrates it
Look for filters certified under NSF 53 / NSF 58 for arsenic removal.