Sierra Vista, AZ Water Quality (ZIP 85635)

Quick Answers

Is ZIP 85635 tap water safe to drink? PFAS compounds have been detected in 85635's water at an average of 10.82 ppt across 7 compounds. A certified pitcher filter or reverse osmosis system is recommended, especially for sensitive populations.

What filter should I use in 85635? Match the filter to the data: reverse osmosis handles PFAS, lead, and arsenic together; NSF-53 pitchers cover the taps you drink from. A basic Brita pitcher will not remove PFAS.

ZIP 85635 Water Quality Summary

EPA testing has detected PFAS "forever chemicals" in the water systems serving ZIP 85635 (Sierra Vista, AZ). Monitoring found a peak of 40 ppt across 3 systems, averaging 10.82 ppt over 7 detected compounds. These levels come from individual EPA UCMR 5 water samples (2023-2025). The EPA's 4 ppt limit for PFOA and PFOS is enforced on a running annual average, so a sample above it shows real exposure but is not by itself a violation.

Contamination Level: MODERATE – Moderate contamination – PFAS detected at meaningful levels; filtration recommended.

Top Detected Compounds in ZIP 85635

• PFOS: 40 ppt (exceeds the EPA 4 ppt limit)
• PFBS: 20 ppt
• PFHXS: 10.9 ppt (exceeds the EPA 10 ppt limit)
• PFOA: 10 ppt (exceeds the EPA 4 ppt limit)
• PFBA: 7 ppt (exceeds the EPA 4 ppt limit)

Lead in ZIP 85635 Water

EPA Lead and Copper Rule testing recorded 50 lead samples for the systems serving 85635, with a 90th-percentile high of 0.0065 mg/L (within the EPA 0.015 mg/L action level). There is no safe level of lead for children; homes built before 1986 should use a certified NSF/ANSI 53 lead filter.

EPA Violations Affecting ZIP 85635

The water systems serving 85635 have 6 health-based EPA Safe Drinking Water Act violations on record, including Lead and Copper Rule Revisions, Revised Total Coliform Rule. A health-based violation means a contaminant exceeded its federal limit or required treatment was not applied.

About the Data

These figures come from EPA UCMR5 (2023-2025) plus Lead and Copper Rule and SDWIS records for the public water system serving ZIP 85635. UCMR5 is the most comprehensive national drinking water survey in US history.

Beyond water: other exposures in Sierra Vista, AZ

Drinking water is one exposure route. These are the other federal datasets that cover ZIP 85635 and Cochise County, AZ.

Radon risk in Cochise County, AZ

The EPA places Cochise County, AZ in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict the radon potential of an area from geology and existing indoor readings - they do not describe any individual home. Radon is the leading cause of lung cancer among people who have never smoked, and the only way to know your own level is a test kit.

Lead paint risk in Cochise County, AZ

Census figures show 40% of homes in Cochise County, AZ were built before 1980, and 10% before 1950. Lead-based paint was banned for residential use in 1978, so older housing stock is the strongest available proxy for lead-paint exposure. This is a statistic about the county's housing, not a test of any particular property - if your home predates 1980, a lead swab test is the way to check.

Air quality in Cochise County, AZ

Modelled annual fine-particle pollution (PM2.5) for Cochise County, AZ averages 5.9 µg/m³, within the EPA's annual PM2.5 standard of 9 µg/m³. PM2.5 is the pollution fraction small enough to reach deep into the lungs. These are CDC modelled estimates for the county as a whole, not a reading taken at this ZIP code.