Hollister Ranch Estates
What EPA’s and California’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.
- Serves
- 150 people
- Connections
- 37
- Water source
- Groundwater
- Based in
- Hollister, CA
- County
- San Benito
- Owner
- Private
- Hardness
- Very hard
The ZIP code it serves
The short answer
1 result is above the limit’s level with no violation recorded, and 1 more is above the health goal. The worst: Arsenic, above the limit’s level, no violation. 7 health-based violations since 2016.
What handles itWhat was found
Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 1.8 ppm, for the period ending Dec. 31, 2001. None since is on file, so it is not counted as a current finding.
Arsenic, uranium, nitrate, total trihalomethanes (TTHM), chromium (total), haloacetic acids (HAA5) and fluoride: California’s own results, samples taken from Jan. 6, 2020 to June 23, 2026, with EPA’s 2012 to 2019 file for earlier years.
Above the limit’s level, no violation recorded1
Arsenic
Comes from the source
11.8ppb
Highest yearly average, 2022 to 2025
Averaged by year, the highest was 11.8 ppb, in 2025, above EPA’s legal limit of 10 ppb. Its highest single sample was 16.9 ppb. That was also the latest year on file. EPA judges this limit on running averages at each sampling point, and recorded no violation for arsenic at this utility since 2020. Results like these with no violation often include water sampled before treatment or blending; the utility’s annual report says what reaches the tap. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.6 ppb, in 2013.
What handles it
- NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
- NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
Above the health goal1
Uranium
Comes from the source
14.5ppb
Highest yearly average, 2020 to 2026
2026 average: 11.2 ppb
Averaged by year, the highest was 14.5 ppb, in 2020: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 34.1 ppb. In 2026, the latest year on file, its 15 samples averaged 11.2 ppb. EPA recorded no violation for uranium at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 32.6 ppb, in 2015, and EPA recorded violations in 2015, 2016 and 2017.
What handles it
- NSF/ANSI 58 look for “Uranium”
Below EPA’s limits5
Nitrate
Comes from the source
9.1ppm
Highest sample; found in 53 of 57
2026 average: 2.5 ppm
The highest sample, in 2023, was 9.1 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its four samples averaged 2.5 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 8.8 ppm, in 2016.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
Total trihalomethanes (TTHM)
Forms or is added in treatment
36ppb
Highest yearly average, 2020 to 2025
2025, one sample: 18 ppb
Averaged by year, the highest was 36 ppb, in 2023, below EPA’s legal limit of 80 ppb. In 2025, the latest year on file, its one sample was 18 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 24 ppb, in 2019.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Chromium (total)
Comes from the source
19.6ppb
Highest yearly average, 2022 to 2025
2025 average: 19.1 ppb
Averaged by year, the highest was 19.6 ppb, in 2022, below EPA’s legal limit of 100 ppb. Its highest single sample was 31.1 ppb. In 2025, the latest year on file, its two samples averaged 19.1 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 21.5 ppb, in 2016.
What handles it
- NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
- NSF/ANSI 53 look for “Chromium Reduction”
Haloacetic acids (HAA5)
Forms or is added in treatment
10ppb
Highest yearly average, 2020 to 2025
2025: not found
Averaged by year, the highest was 10 ppb, in 2023, below EPA’s legal limit of 60 ppb. In 2025, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 5.0 ppb, in 2019.
What handles it
No certification claim covers this compound yet.
Fluoride
Forms or is added in treatment
0.25ppm
Highest yearly average, 2022 to 2025
2025 average: 0.25 ppm
Averaged by year, the highest was 0.25 ppm, in 2022, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.3 ppm. In 2025, the latest year on file, its two samples averaged 0.25 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.35 ppm, in 2016.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Lead
What handles it
A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”
- NSF/ANSI 53
Claim: Arsenic (Pentavalent)<=50 ppb Reduction
For: Arsenic
Other certifiers’ wording: Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claims: Arsenic (Pentavalent)<=50 ppb Reduction, Uranium
For: Arsenic, Uranium
Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)
At the tap, or for the whole house?
These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. How whole-house systems compare.
Filters with those claims on a certifier’s listing
Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Arsenic
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: Arsenic
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: Arsenic
Hardness
Very hard, typically 724 mg/L (42.3 grains per gallon), across 3 sampling points, 2019 to 2025.
Hardness is calcium and magnesium. EPA sets no limit for it: it shows up as scale on fixtures and in water heaters, and as soap that won’t lather. USGS calls water above 60 mg/L moderately hard, above 120 hard and above 180 very hard.
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Combined Uranium | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2017 to Sept. 30, 2017 | 22 PCI/L | Resolved |
| Combined Uranium | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2017 to June 30, 2017 | 22 PCI/L | Resolved |
| Combined Uranium | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2017 to March 31, 2017 | 23 PCI/L | Resolved |
| Combined Uranium | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2016 to Dec. 31, 2016 | 23 PCI/L | Resolved |
| Combined Uranium | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2016 to Sept. 30, 2016 | 24 PCI/L | Resolved |
| Combined Uranium | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2016 to June 30, 2016 | 24 PCI/L | Resolved |
| Combined Uranium | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2016 to March 31, 2016 | 25 PCI/L | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 4 monitoring or reporting violations not shown. | ||||
What this report can’t tell you
Everything else. Arsenic, uranium, nitrate, total trihalomethanes (TTHM), chromium (total), haloacetic acids (HAA5) and fluoride results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Hollister Ranch Estates’s own annual report, which it must send you every year, has the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; California’s results run from Jan. 6, 2020 to June 23, 2026.
Testing your own tap
The 3 labs California certifies closest to the area Hollister Ranch Estates serves, 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 13 miles
Certified for bacteria
Monterey County Consolidated Environmental Laboratory
Salinas, CA · about 21 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics
Bracewell Engineering, Inc.
Morgan Hill, CA · about 22 miles
Certified for bacteria, nitrate, minerals and other inorganics
Sources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- California State Water Resources Control Board, Division of Drinking Water, results from Jan. 1, 2020 to July 17, 2026, read Oct. 8, 2026
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: California State Water Resources Control Board, ELAP accredited laboratories and their fields of accreditation, read Oct. 17, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Hardness: California State Water Resources Control Board, Division of Drinking Water, results from Dec. 9, 2019 to Dec. 10, 2025, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID CA3500904. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on the 2 results above a lineWhat each one does to health, where it comes from, and the certification claim that addresses it.Start with Arsenic
- Get the utility’s own reportHollister Ranch Estates must send you a water quality report every year. It covers contaminants this page does not show.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs