Gilroy, CA tap water
Supplied mostly by City of Gilroy, plus 1 other utility. Here's what the water means for your fish.
Disinfectant
Chlorine or chloramine
Utilities here use chlorine or chloramine, depending on which one serves your address. Chlorine slowly gases off from standing water; chloramine doesn't.
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 (2025–2026).
Nitrate (NO₃)
1.5–37 ppm (Low)
Typical 1.5 ppm
Low, so water changes lower your tank's nitrate well.
From California Water Board lab results, measured before treatment; California Water Board lab results (2023–2026).
Copper at home taps
Up to 0.07 ppm (Low)
Typically not detected
Not detected in testing. Water that sits in household pipes overnight can still pick some up.
From California Water Board lab results (2024–2026).
Water chemistry
General hardness
102–286 ppm
Typical 102 ppm
Moderately soft to medium. Suits most community fish and plants.
From California Water Board lab results, measured before treatment; California Water Board lab results (2024–2026).
Carbonate hardness (alkalinity)
68–234 ppm
Typical 68 ppm
Moderate buffering. pH should stay fairly steady.
From California Water Board lab results, measured before treatment; California Water Board lab results (2024–2026).
pH
7.6–8
Typical 7.6
Most community fish do well here. Stable water matters more than the exact number.
From California Water Board lab results, measured before treatment; California Water Board lab results (2024–2026).
Total dissolved solids
279–368 ppm
Typical 279 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, measured before treatment; California Water Board lab results (2024–2026).
- Santa Clara Valley Water District adds phosphate to protect pipes. It can feed algae in tanks without much plant growth.
Who supplies Gilroy, CA
City of Gilroy
Serves 50% of residents · Groundwater (wells) · Chlorine
Santa Clara Valley Water District
Serves 50% of residents · Lake or river water · Chloramine
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.