Serving roughly 26,017 people in San Benito County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
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Results for HOLLISTER, CITY OF
1 water provider directly on file, serving roughly 26,017 people in San Benito County, California.
Quick answer: HOLLISTER, CITY OF has no violations on file and no single reading stands out against its peers (149 other providers in this area). It serves roughly 26,017 people, and the full breakdown below reflects everything EPA and California have on record for it.
Lead Summary
Lithium
Totalhaloaceticacids (HAA5)
TTHM
Bromoform
Bromodichloromethane
Dibromochloromethane
Chloroform
Dichloroaceticacid
Dibromoaceticacid
Trichloroaceticacid
Magnesium
Sodium
Calcium
Alkalinity, Total
Alkalinity, Bicarbonate
Hardness, Total (ASCACO3)
TDS
Chloride
Sulfate
Nitrate
Potassium
pH
Chromium, Hex
Boron, Total
Iron
Conductivity (at 25°C)
Utility HOLLISTER, CITY OFPopulation served 26,017Owner Local government
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.0023 mg/L (ppm)
12/31/2023
Chromium, Hex
Detected: 10.6 UG/L (ppb)
9/11/2025
Iron
Detected: 160 UG/L (ppb)
1/29/2025
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 11 UG/L (ppb)
9/10/2025
TTHM
Detected: 39.14 UG/L (ppb)
9/10/2025
A group of disinfection byproducts formed when chlorine reacts with organic matter. Long-term exposure above the legal limit has been linked to increased cancer risk in some studies.
Bromoform
Detected: 15.05 UG/L (ppb)
9/10/2025
Bromodichloromethane
Detected: 5.81 UG/L (ppb)
9/10/2025
Dibromochloromethane
Detected: 16.32 UG/L (ppb)
9/10/2025
Chloroform
Detected: 1.96 UG/L (ppb)
9/10/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Chloride
Detected: 26 MG/L (ppm)
4/16/2025
Sulfate
Detected: 25 MG/L (ppm)
4/16/2025
Nitrate
Detected: 5.5 MG/L (ppm)
7/16/2025
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Boron, Total
Detected: 830 UG/L (ppb)
4/16/2025
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 6.1 MG/L (ppm)
4/16/2025
Sodium
Detected: 19 MG/L (ppm)
4/16/2025
Calcium
Detected: 32 MG/L (ppm)
4/16/2025
Potassium
Detected: 2.9 MG/L (ppm)
4/16/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 104 MG/L (ppm)
4/16/2025
pH
Detected: 6.95 PH
4/16/2025
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
Lithium
Detected: 22 µg/L (ppb)
8/15/2024
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 72 MG/L (ppm)
4/16/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 1.4 UG/L (ppb)
9/10/2025
Dibromoaceticacid
Detected: 5.5 UG/L (ppb)
9/10/2025
Trichloroaceticacid
Detected: 5.5 UG/L (ppb)
9/10/2025
Alkalinity, Total
Detected: 72 MG/L (ppm)
4/16/2025
TDS
Detected: 170 MG/L (ppm)
4/16/2025
Conductivity (at 25°C)
Detected: 280 UMHO/CM
4/16/2025
Filtration considerations: See the table below for how whole-house carbon, under-sink reverse osmosis, and under-sink carbon systems compare against what's actually on file here. These are general system types, not a specific product recommendation.