What was found in Hollister's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate-Nitrite | 4810 µg/L 48% of the EPA limit 10000 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 673000 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 18/20 | SYR4 |
| Nitrate | 8588 µg/L 86% of the EPA limit 10000 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 11752 µg/L — VALENZUELA WATER SYSTEM · 55 people · 2019 | 19/20 | SYR4 |
| Copper | 96.5 µg/L 7.4% of the EPA limit 1300 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2017
Highest in the city: 1100 µg/L — SAN JUSTO MUTUAL WATER COMPANY · 160 people · 2019 | 7/20 | SYR4 |
| Fluoride | 365 µg/L 9.1% of the EPA limit 4000 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2017
Highest in the city: 518 µg/L — VENTURE ESTATES MWC · 50 people · 2018 | 19/20 | SYR4 |
| Barium | 413.7 µg/L 21% of the EPA limit 2000 µg/L Highest in the city: WHISPERING PINES INN · 38 people · 2019 | 12/20 | SYR4 |
| Nitrite | 400 µg/L 40% of the EPA limit 1000 µg/L Highest in the city: WHISPERING PINES INN · 38 people · 2019 | 5/20 | SYR4 |
| Arsenic | 4.195 µg/L 42% of the EPA limit 10 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2017
Highest in the city: 181.3 µg/L — WHISPERING PINES INN · 38 people · 2019 | 16/20 | SYR4 |
| TTHM | 100.256 µg/L 125% of the EPA limit, at the 95th percentile of samples — 80 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 157.439 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 18/20 | SYR4 |
| Dibromochloromethane | 33.292 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 67.12 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 13/20 | SYR4 |
| Bromoform | 62.668 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019 | 17/20 | SYR4 |
| Chromium | 28.75 µg/L 29% of the EPA limit 100 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2017
Highest in the city: 41 µg/L — ASHFORD HIGHLANDS MWC · 132 people · 2017 | 11/20 | SYR4 |
| Combined Uranium | 8.4334 µg/L 28% of the EPA limit 30 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2017
Highest in the city: 35.164 µg/L — HOLLISTER RANCH ESTATES · 150 people · 2019 | 10/20 | SYR4 |
| Lead | 11 µg/L 73% of the EPA limit 15 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2014
Highest in the city: 35 µg/L — SAN JUSTO MUTUAL WATER COMPANY · 160 people · 2019 | 2/20 | SYR4 |
| Bromodichloromethane | 11.35 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 34.164 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 13/20 | SYR4 |
| Lithium | 29 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2024 | 2/20 | UCMR-5 |
| Total Haloacetic Acids (HAA5) | 18.59 µg/L 31% of the EPA limit 60 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 28.62 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 13/20 | SYR4 |
| Asbestos | 25.25 MFL 361% of the EPA limit, at the 95th percentile of samples — 7 MFL Highest in the city: ASHFORD HIGHLANDS MWC · 132 people · 2016 | 1/20 | SYR4 |
| Dibromoacetic Acid | 14.925 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 15.82 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 17/20 | SYR4 |
| Dichloroacetic Acid | 3.15 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 10.28 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 9/20 | SYR4 |
| Chloroform | 4.038 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 9.15 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 9/20 | SYR4 |
| Selenium | 6.56 µg/L 13% of the EPA limit 50 µg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2017
Highest in the city: 8.48 µg/L — HOLLISTER RANCH ESTATES · 150 people · 2019 | 9/20 | SYR4 |
| Gross Beta Particle Activity | 8.1345 pCi/L No EPA limit set Highest in the city: HOLLISTER RANCH ESTATES · 150 people · 2016 | 1/20 | SYR4 |
| Trichloroacetic Acid | 4.85 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 7.1 µg/L — VENTURE ESTATES MWC · 50 people · 2019 | 7/20 | SYR4 |
| Monochloroacetic Acid | 4.5 µg/L No EPA limit set Highest in the city: CSA NO. 31 STONEGATE WS · 230 people · 2019 | 2/20 | SYR4 |
| Combined Radium (-226 And -228) | 3.88 pCi/L 78% of the EPA limit 5 pCi/L Highest in the city: ROSA MORADA MUTUAL WATER COMPANY · 138 people · 2018 | 3/20 | SYR4 |
| Monobromoacetic Acid | 2.39 µg/L No EPA limit set Main supplier: HOLLISTER, CITY OF · 26,017 people · 2019
Highest in the city: 3 µg/L — CSA NO. 31 STONEGATE WS · 230 people · 2019 | 5/20 | SYR4 |
| Toluene | 2.3 µg/L 0.2% of the EPA limit 1000 µg/L Highest in the city: SPRINGWOOD ESTATES MWC · 50 people · 2019 | 2/20 | SYR4 |
| Antimony, Total | 2 µg/L 33% of the EPA limit 6 µg/L Highest in the city: WHISPERING PINES INN · 38 people · 2019 | 1/20 | SYR4 |
| Cadmium | 0.5000 µg/L 10% of the EPA limit 5 µg/L Highest in the city: WHISPERING PINES INN · 38 people · 2019 | 1/20 | SYR4 |
| Lead | 0.0023 mg/L 15% of the EPA limit 0.0150 mg/L Main supplier: HOLLISTER, CITY OF · 26,017 people · 2023
Highest in the city: 0.0453 mg/L — CREEKBRIDGE MUTUAL WATER COMPANY · 69 people · 2025 | 19/20 | LCR |
| PFOA | 0.0046 µg/L No EPA limit set Highest in the city: SUNNYSLOPE COUNTY WATER DIST · 24,954 people · 2025 | 1/20 | UCMR-5 |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Hollister
Frequently asked questions about Hollister tap water
Is Hollister tap water safe to drink?
EPA testing detected 31 contaminants in the water serving Hollister. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Hollister?
20 public water suppliers report drinking-water monitoring for Hollister, California to the EPA. Each is listed above with its population served.
What contaminants are in Hollister's water?
The contaminants EPA monitoring detected in Hollister include Nitrate-Nitrite, Nitrate, Copper, Fluoride, Barium. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.