Palo Alto, CA tap water
Supplied mostly by Santa Clara Valley Water District, plus 1 other utility. Here's what the water means for your fish.
Disinfectant
Chloramine
Your water is treated with chloramine. Unlike chlorine, it doesn't gas off when water sits out, and many pitcher and fridge filters aren't rated to remove it. Conditioners that list chloramine on the label break it apart, which frees a little ammonia. Some utilities switch to plain chlorine for a few weeks a year.
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)
Up to 1.9 ppm (Low)
Typical 1.5 ppm
Low, so water changes lower your tank's nitrate well.
From California Water Board lab results; San Francisco Regional Water System, which supplies City of Palo Alto (2023–2026).
Copper at home taps
Not detected (Low)
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
8–106 ppm
Typical 102 ppm
Moderately soft to medium. Suits most community fish and plants.
From California Water Board lab results; San Francisco Regional Water System, which supplies City of Palo Alto (2023–2026).
Carbonate hardness (alkalinity)
8–102 ppm
Typical 68 ppm
Moderate buffering. pH should stay fairly steady.
From California Water Board lab results; San Francisco Regional Water System, which supplies City of Palo Alto (2023–2026).
pH
7.6–9
Typical 7.6
Most community fish do well here. Stable water matters more than the exact number.
From California Water Board lab results; San Francisco Regional Water System, which supplies City of Palo Alto (2023–2026).
Total dissolved solids
24–279 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; San Francisco Regional Water System, which supplies City of Palo Alto (2023–2026).
- Santa Clara Valley Water District adds phosphate to protect pipes. It can feed algae in tanks without much plant growth.
Who supplies Palo Alto, CA
Santa Clara Valley Water District
Serves 51% of residents · Lake or river water · Chloramine
City of Palo Alto
Serves 51% of residents · Buys water from San Francisco Regional Water System · 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.