Arsenic in Paso Robles, CA Drinking Water
Arsenic data for Paso Robles, California · 35,658 residents · 2 ZIP codes
Routine testing in Paso Robles, California turned up Arsenic — samples from the public supply came back positive, placing this contaminant on the list of substances residents here have a concrete reason to look into.
Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-05-14
Arsenic in Paso Robles Tap Water
Arsenic has been detected in Paso Robles, California drinking water at a maximum level of 7.7 ppb — below the EPA MCL of 10 ppb.
This analysis covers 35,658 residents across 2 ZIP codes in Paso Robles.
Paso Robles's overall water quality grade is D (50/100).
Is Arsenic in Paso Robles Water Safe?
Arsenic was detected in Paso Robles water but currently falls within EPA limits. However, some health organizations argue the EPA MCL may not be protective enough.
If you are concerned, a reverse osmosis filter can reduce arsenic levels further.
Arsenic Levels by ZIP Code
Average arsenic level across Paso Robles: 7.7 ppb
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 Paso Robles 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.