San Martin, CA tap water
Supplied mostly by Santa Clara Valley Water District, plus 2 other utilities. 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; EPA monitoring data (2013–2026).
Nitrate (NO₃)
1.5–46 ppm (Low)
Typical 1.5 ppm
Low, so water changes lower your tank's nitrate well.
From California Water Board lab results; EPA monitoring data; California Water Board lab results, measured before treatment (2013–2026).
Copper at home taps
Up to 0.13 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 (2023–2026).
Water chemistry
General hardness
102–248 ppm
Typical 102 ppm
Moderately soft to medium. Suits most community fish and plants.
From California Water Board lab results; California Water Board lab results, measured before treatment (2023–2026).
Carbonate hardness (alkalinity)
68–174 ppm
Typical 68 ppm
Moderate buffering. pH should stay fairly steady.
From California Water Board lab results; California Water Board lab results, measured before treatment (2023–2026).
pH
7.6–8.2
Typical 7.6
Most community fish do well here. Stable water matters more than the exact number.
From California Water Board lab results; EPA monitoring data; California Water Board lab results, measured before treatment (2013–2026).
Total dissolved solids
279–351 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; California Water Board lab results, measured before treatment; San Martin County Water District's conductivity readings (2023–2026).
- Santa Clara Valley Water District adds phosphate to protect pipes. It can feed algae in tanks without much plant growth.
Who supplies San Martin, CA
Santa Clara Valley Water District
Serves 83% of residents · Lake or river water · Chloramine
Cal Am - West San Martin
Serves 8% of residents · Groundwater (wells) · Chlorine
San Martin County Water District
Serves 6% of residents · Groundwater (wells) · 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.
Tap water lookup covers US cities only for now. Want to know why it matters? Read our story on tap water.
Compiled by Shoal & Stem from public records. Free to cite with a link.