Is Tres Pinos, CA tap water safe?
The short answer
1 of the 3 utilities serving Tres Pinos has a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and California’s records: City of Hollister.
City of Hollister, which serves the most people here, has 1 result above the legal limit, 3 results above the health goal and 1 result above EPA’s health benchmark. The worst: Total trihalomethanes (TTHM) at 44.5 ppb, above the legal limit.
The water from City of Hollister is moderately hard to very hard depending on the source, 91 to 509 mg/L (5.3 to 29.8 grains per gallon). How California’s water compares.
A town can be served by more than one utility, and some homes are on private wells. The name on your water bill tells you which is yours, and your ZIP code narrows it down. They are listed by how many people each serves in Tres Pinos’s ZIP codes, from EPA’s estimates.
- Open report
City of Hollister
California · serves 26,598 people · under 100 in Tres Pinos
1 result above the legal limit, 3 results above the health goal and 1 result above EPA’s health benchmark. The worst: Total trihalomethanes (TTHM) at 44.5 ppb, above the legal limit. Hardness: moderately hard to very hard depending on the source, 91 to 509 mg/L (5.3 to 29.8 grains per gallon).
4 health-based violations since 2016
- Open report
Sunnyslope County Water Dist
California · serves 25,486 people · under 100 in Tres Pinos
2 results above EPA’s new limit, which takes effect in 2029, 2 results above the health goal and 1 result above EPA’s health benchmark. The worst: PFOA at 5.8 ppt, above EPA’s new limit, which takes effect in 2029. Hardness: very hard, typically 401 mg/L (23.5 grains per gallon).
No health-based violations since 2016
- Open report
Tres Pinos CWD
California · serves 350 people · under 100 in Tres Pinos
2 results above the health goal. The worst: Arsenic at 2.0 ppb, above the health goal. Hardness: very hard, 563 mg/L (32.9 grains per gallon).
No health-based violations since 2016
What handles it
Each of these is certified, on a certifier’s listing, for a result above a line in City of Hollister’s water, which serves the most people here. Another utility’s report names what handles its own results.
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Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Total trihalomethanes (TTHM), Arsenic, Lead
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Total trihalomethanes (TTHM), Arsenic, Lead
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Total trihalomethanes (TTHM), Arsenic, Lead
Water testing near Tres Pinos
The 3 labs California certifies closest to Tres Pinos, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
CM Analytical, Inc.
Gilroy, CA · about 20 miles
Certified for bacteria
Monterey County Consolidated Environmental Laboratory
Salinas, CA · about 24 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics
Bracewell Engineering, Inc.
Morgan Hill, CA · about 29 miles
Certified for bacteria, nitrate, minerals and other inorganics
Which ZIP codes are in Tres Pinos: Census 2020 relationship files. Which utilities serve them, and how many people: EPA SDWIS and EPA’s service area map. Each utility’s results: EPA UCMR 5, EPA SDWIS, and EPA’s and the state’s compliance monitoring, as its report lists them. How they are measured: methodology. Certified labs: California State Water Resources Control Board, ELAP accredited laboratories and their fields of accreditation; distances from the Census 2020 ZIP code tabulation area gazetteer.
Near Tres Pinos
Other towns in San Benito County with a page of their own.
What to do next
- Read City of Hollister’s full reportEvery result with its dates, the violations, and the certification claim that handles each finding.Open the report
- About Total trihalomethanes (TTHM)What it does to health, where it comes from, and the certification claim that addresses it.About Total trihalomethanes (TTHM)
- On a private well?No utility tests a well. A certified lab test is the first step.How to test well water