Hollister, CA tap water
Supplied mostly by City of Hollister, plus 1 other utility. Here's what the water means for your fish.
Disinfectant
Chlorine
Your water is treated with chlorine. It slowly gases off from standing water, and any water conditioner removes it.
Safety for fish and shrimp
Nitrite (NO₂)
Not detected (Low)
Not detected in testing, so any nitrite in your tank comes from the tank itself.
From California Water Board lab results (2025).
Nitrate (NO₃)
Not detected (Low)
Not detected in testing, so water changes lower your tank's nitrate well.
From California Water Board lab results; EPA monitoring data (2016–2025).
Copper at home taps
Up to 0.02 ppm (Low)
Typical 0.02 ppm
Low. Water that sits in household pipes overnight can carry more than this.
From California Water Board lab results (2023).
Water chemistry
General hardness
110–240 ppm
Typical 142 ppm
Moderately soft to medium. Suits most community fish and plants.
From California Water Board lab results; San Benito County Water District and City of Hollister, which supplies Sunnyslope County Water Dist (2023–2026).
Carbonate hardness (alkalinity)
67–153 ppm
Typical 97 ppm
Moderate buffering. pH should stay fairly steady.
From California Water Board lab results; San Benito County Water District and City of Hollister, which supplies Sunnyslope County Water Dist (2023–2026).
pH
8.2–8.3
Typical 8.3
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From California Water Board lab results; EPA monitoring data (2016–2025).
Total dissolved solids
220–285 ppm
Typical 220 ppm
A rough measure of everything dissolved in the water. RO water reads near 0, so TDS is a quick way to compare waters.
From California Water Board lab results; San Benito County Water District and City of Hollister, which supplies Sunnyslope County Water Dist (2023–2026).
Who supplies Hollister, CA
City of Hollister
Serves 60% of residents · Buys water from San Benito County Water District · Chlorine
Sunnyslope County Water Dist
Serves 32% of residents · Buys water from San Benito County Water District · Chlorine
Our data comes from public records and is still incomplete. Many utilities don't publish every number, so we're adding more all the time. Your city's range is a starting point: testing your own tap is the only way to know exactly what's in it.
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Compiled by Shoal & Stem from public records. Free to cite with a link.