Is Hollister, CA Tap Water Safe to Drink?
Graded F — but Copper, Chromium-6 and 1 more were detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
37.8/100
waterverge.com Hollister, CA — Water Quality Report
Hollister's drinking water received a grade of F (37.8 out of 100), indicating failing water quality. The city's 21 water systems serve approximately 53,795 residents using purchased surface water.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. UCMR 5 testing detected 2 PFAS compounds, with levels exceeding EPA maximum contaminant levels in the water supply.
The system has 356 violations on record, including 132 health-based violations. 35 remain unresolved.
What to know about Hollister's water
Hollister ranks #684 out of 694 cities in California for water quality, placing it among the lowest-rated in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
Of particular concern: PFAS "forever chemical" levels exceed the 2024 EPA maximum contaminant levels. These synthetic compounds don't break down naturally and require specialized filtration such as reverse osmosis or granular activated carbon.
Hexavalent chromium (chromium-6) was detected at 18.00 µg/L, above California's 10 µg/L limit. There is no federal MCL, but the EPA is reviewing evidence linking long-term exposure to cancer risk.
The system has seen 28 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Hollister, CA water safe to drink?
Hollister's drinking water has significant quality concerns based on EPA testing data. With a grade of F (37.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 21 water systems serve approximately 53,795 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Hollister
A timeline of significant water quality events, violations, and data updates.
PFAS levels exceed EPA maximum contaminant levels. Reverse osmosis or activated carbon filtration recommended.
Latest EPA compliance and testing data incorporated into Hollister's water quality assessment. Grade: F (37.8/100).
Contaminants: Lead and Copper Rule.
Contaminants: TTHM, Total Haloacetic Acids (HAA5).
Contaminants: Revised Total Coliform Rule.
Federal disaster declaration (FEMA DR-3592). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Hollister's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
PFAS "forever chemicals" exceed EPA maximum contaminant levels. Reverse osmosis or granular activated carbon filtration strongly recommended.
The "Erin Brockovich" chemical. There is no federal MCL, but California has set a limit of 10 µg/L. Reverse osmosis filtration is effective at removing hexavalent chromium.
PFAS "forever chemicals" detected
UCMR 5 testing found 2 PFAS compounds in Hollister's water supply. PFAS are synthetic chemicals that persist indefinitely in the environment and the human body.
Violation history
Hollister's water system has 356 total violations on record, including 132 health-based violations. 35 remain unresolved. 28 violations were issued in the last 5 years.
Flood & environmental risk
San Benito County has experienced 8 federally declared disasters since 1969. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Pacheco C Nr Dunneville, Llagas C Nr Gilroy, Tres Pinos C Nr Tres Pinos, San Benito R Bl Hospital Rd Bridge Nr Hollister.
Where does Hollister's water come from?
Hollister's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 21 water systems serving approximately 53,795 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Pacheco C Nr Dunneville (river), Llagas C Nr Gilroy (river), Tres Pinos C Nr Tres Pinos (river), San Benito R Bl Hospital Rd Bridge Nr Hollister (river).
What Hollister residents can do
Recommended: Reverse osmosis system. This addresses the specific contaminants found in Hollister's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Hollister's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Forever chemicals overview
National PFAS report →Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Hollister
Industrial polluters nearby
Reported releases to surface water by facilities near Hollister, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
FUJIFILM ELECTRONIC MATERIALS USA INC. HOLLISTER, CA95023 | — | — | 2.5 mi |
PACIFIC SCIENTIFIC ENERGETICS MATERIALS CO CALIFORNIA HOLLISTER, CA95023 | — | — | 3.2 mi |
TRICAL INC HOLLISTER, CA95023 | — | — | 8.4 mi |
PRIDE CONVEYANCE SYSTEMS HOLLISTER, CA95023 | — | — | 2.1 mi |
ROYAL CIRCUIT SOLUTIONS INC. HOLLISTER, CA95023 | — | — | 1.9 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
San Benito County has experienced 8 federally declared disasters since 1969. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Hollister's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.85 | 1.3 | mg/L | Inorganic | Over Limit |
| 11Cl-PF3OUdS | ND | HI | µg/L | PFAS | Not Detected |
| 4:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 6:2 FTS 6:2 FTSPFAS A fluorotelomer sulfonate commonly found at sites contaminated with aqueous film-forming foam (AFFF) used in firefighting. Health EffectsPotential liver toxicity and endocrine disruption. Less studied but identified as a contaminant of concern. EPA LimitNo individual MCL (not yet regulated) Common SourcesFirefighting foam (AFFF), airports, military bases, and industrial facilities. | ND | HI | µg/L | PFAS | Not Detected |
| 8:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 9Cl-PF3ONS | ND | HI | µg/L | PFAS | Not Detected |
| ADONA | ND | HI | µg/L | PFAS | Not Detected |
| HFPO-DA HFPO-DA (GenX)PFAS A replacement for PFOA in manufacturing, marketed as safer but still a persistent "forever chemical." Also known as GenX. Health EffectsLiver and kidney effects, reproductive toxicity, immune system effects, and potential cancer risk. EPA Limit10 ppt MCL Common SourcesFluoropolymer manufacturing (used as PFOA replacement), industrial wastewater discharge. | ND | 0.01 | µg/L | PFAS | Not Detected |
| lithium LithiumInorganic A naturally occurring alkali metal found in groundwater. Monitored under UCMR 5 to assess occurrence in drinking water. Health EffectsKidney effects at high doses. Low-level exposure effects under study; some research suggests neurological effects. EPA LimitNo MCL (monitoring only under UCMR 5) Common SourcesNatural mineral deposits, geothermal water, and industrial discharge. | 29.000 | HI | µg/L | PFAS | Detected |
| NEtFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| NFDHA | ND | HI | µg/L | PFAS | Not Detected |
| NMeFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| PFBA PFBAPFAS One of the shortest-chain PFAS compounds. Very mobile in water and difficult to remove with standard filtration. Health EffectsThyroid effects, potential developmental toxicity. Shorter half-life in body than long-chain PFAS. EPA LimitNo individual MCL (not yet regulated) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and firefighting foam. | ND | HI | µg/L | PFAS | Not Detected |
| PFBS PFBSPFAS A short-chain PFAS used as a replacement for PFOS. While it clears the body faster than long-chain PFAS, it still persists in the environment. Health EffectsThyroid effects, reproductive and developmental toxicity, kidney effects. EPA LimitPart of Hazard Index (1.0) Common SourcesIndustrial discharge, firefighting foam, and as a replacement chemical in manufacturing. | ND | HI | µg/L | PFAS | Not Detected |
| PFDA | ND | HI | µg/L | PFAS | Not Detected |
| PFDoA | ND | HI | µg/L | PFAS | Not Detected |
| PFEESA | ND | HI | µg/L | PFAS | Not Detected |
| PFHpA PFHpAPFAS A medium-chain PFAS compound found in various environmental samples. Less studied than PFOA/PFOS but still considered a contaminant of concern. Health EffectsLiver effects, potential developmental toxicity, and endocrine disruption. EPA LimitPart of Hazard Index (1.0) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFHpS | ND | HI | µg/L | PFAS | Not Detected |
| PFHxA PFHxAPFAS A short-chain PFAS replacement chemical widely used after manufacturers phased out longer-chain PFAS. Very commonly detected in water. Health EffectsLiver and kidney effects, potential thyroid disruption. Considered less toxic than long-chain PFAS but still persistent. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial processes, firefighting foam (AFFF), food packaging, and textile treatment. | ND | HI | µg/L | PFAS | Not Detected |
| PFHxS PFHxSPFAS A medium-chain PFAS found in firefighting foam and consumer products. It has a long half-life in the human body, similar to long-chain PFAS. Health EffectsImmune system effects, thyroid disruption, and potential reproductive and developmental harm. EPA LimitPart of Hazard Index (1.0) Common SourcesFirefighting foam (AFFF), waterproof textiles, food packaging, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| PFMBA | ND | HI | µg/L | PFAS | Not Detected |
| PFMPA | ND | HI | µg/L | PFAS | Not Detected |
| PFNA PFNAPFAS A long-chain PFAS compound used in manufacturing fluoropolymers. It bioaccumulates in the body and is very persistent in the environment. Health EffectsDevelopmental effects, liver toxicity, immune suppression, and potential cancer risk. EPA LimitPart of Hazard Index (1.0) Common SourcesFluoropolymer manufacturing, industrial emissions, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFOA PFOAPFAS A long-chain PFAS ("forever chemical") once widely used in nonstick coatings and firefighting foam. It persists in the body and environment for years. Health EffectsLinked to kidney and testicular cancer, thyroid disease, elevated cholesterol, and reproductive issues. EPA Limit4.0 ppt MCL Common SourcesIndustrial discharge, firefighting foam (AFFF), nonstick cookware manufacturing, and contaminated groundwater. | 0.005 | 0.004 | µg/L | PFAS | Over MCL |
| PFOS PFOSPFAS A long-chain PFAS compound historically used in stain-resistant coatings and firefighting foam. One of the most studied and persistent PFAS chemicals. Health EffectsLiver damage, immune system suppression, thyroid disruption, increased cholesterol, and potential cancer risk. EPA Limit4.0 ppt MCL Common SourcesFirefighting foam (AFFF), industrial sites, stain-resistant fabric treatments, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFPeA PFPeAPFAS A short-chain PFAS compound commonly detected in drinking water. One of the most frequently found PFAS in UCMR 5 monitoring. Health EffectsLess studied than PFOA/PFOS. Potential liver and thyroid effects. Research is ongoing. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial discharge, firefighting foam degradation, and consumer products. | ND | HI | µg/L | PFAS | Not Detected |
| PFPeS | ND | HI | µg/L | PFAS | Not Detected |
| PFTA | ND | HI | µg/L | PFAS | Not Detected |
| PFTrDA | ND | HI | µg/L | PFAS | Not Detected |
| PFUnA | ND | HI | µg/L | PFAS | Not Detected |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Hollister compares by contaminant
Explore where Hollister ranks among all California cities for specific contaminants.
Water source & infrastructure
Where Hollister's water comes from
Hollister's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 53,795 people through 21 water systems.
Water bodies near Hollister
Hollister is located near 4 notable water bodies. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Hollister
| System Name | PWSID | Population | Source |
|---|---|---|---|
| HOLLISTER, CITY OF | CA3510001 | 26,017 | SWP |
| SUNNYSLOPE COUNTY WATER DIST | CA3510003 | 24,954 | SWP |
| RANCHO SAN JOAQUIN MWC | CA3500581 | 914 | GW |
| CASA DE FRUTA WATER SYSTEM | CA4300611 | 250 | GW |
| CSA NO. 31 STONEGATE WS | CA3500006 | 230 | SW |
| SAN JUSTO MUTUAL WATER COMPANY | CA3500550 | 160 | GW |
| HOLLISTER RANCH ESTATES | CA3500904 | 150 | GW |
| ROSA MORADA MUTUAL WATER COMPANY | CA3500549 | 138 | GW |
| ASHFORD HIGHLANDS MWC | CA3500900 | 132 | GW |
| DUNNEVILLE ESTATES CSA #50 | CA3500910 | 120 | GW |
| MCMAHON ROAD MUTUAL WATER COMPANY | CA3500510 | 102 | GW |
| COMSTOCK MUTUAL WATER COMPANY | CA3500912 | 100 | GW |
| UNION HEIGHTS MWC | CA3500825 | 98 | GW |
| VINEYARD ESTATES MWC | CA3500579 | 90 | GW |
| CREEKBRIDGE MUTUAL WATER COMPANY | CA3500911 | 69 | GW |
| VALENZUELA WATER SYSTEM | CA3500527 | 55 | GW |
| CASA DE FRUTA ORCHARDS | CA3500511 | 53 | GW |
| VENTURE ESTATES MWC | CA3500552 | 50 | GW |
| SPRINGWOOD ESTATES MWC | CA3500575 | 50 | GW |
| WHISPERING PINES INN | CA3500810 | 38 | GW |
| SAN BENITO COUNTY WATER DISTRICT | CA3510007 | 25 | SW |
How Hollister compares
Full California rankings →Hollister's score of 37.8/100 is below the average of 57/100 among major California cities. It outscores 3 of 10 nearby cities. 7 of 10 nearby cities score higher.
Nearby cities
View California rankings →About Hollister, CA
Learn more about your water
Guides and resources related to Hollister's water quality findings.
Explore water quality across San Benito
Frequently asked questions
Is Hollister, CA tap water safe to drink?
Hollister's water quality earned a grade of F (37.8/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #684 out of 694 cities tested in California.
What contaminants are in Hollister's water?
Lead was measured at 0.0 ppb (90th percentile). 2 PFAS compounds were detected. 356 violations are on record.
How is Hollister's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Hollister?
PFAS compounds exceed EPA limits — a reverse osmosis or activated carbon filter is recommended.
Where does Hollister's water come from?
Hollister's water is sourced from Purchased surface water. The city has 21 water systems serving approximately 53,795 residents.
What health violations has Hollister's water system had?
Hollister has 132 health-based violations on record. The most recent violation was recorded in October 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 35 violations remain unresolved.
How does Hollister's water compare to other cities?
Hollister ranks #684 out of 694 cities in California (better than 1% of state cities) and #15391 out of 15744 cities nationally (2th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.