Menlo Park, CA tap water
Supplied mostly by California Water Service - Bear Gulch, 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 (2023–2026).
Nitrate (NO₃)
Up to 1.9 ppm (Low)
Typically not detected
Not detected in testing, so water changes lower your tank's nitrate well.
From California Water Board lab results; San Francisco Regional Water System and Sfpuc City Distribution Division, which supplies Menlo Park Municipal Water (2013–2026).
Copper at home taps
0.02–0.03 ppm (Low)
Typical 0.03 ppm
Low. Water that sits in household pipes overnight can carry more than this.
From California Water Board lab results (2024).
Water chemistry
General hardness
8–190 ppm
Typical 190 ppm
Moderately hard. Great for livebearers, and most community fish adapt.
From California Water Board lab results; San Francisco Regional Water System and Sfpuc City Distribution Division, which supplies Menlo Park Municipal Water (2023–2025).
Carbonate hardness (alkalinity)
8–110 ppm
Typical 110 ppm
Strong buffering. pH stays steady and hard to lower without RO water.
From California Water Board lab results; San Francisco Regional Water System and Sfpuc City Distribution Division, which supplies Menlo Park Municipal Water (2023–2025).
pH
8.1–9.2
Typical 8.8
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From California Water Board lab results; San Francisco Regional Water System and Sfpuc City Distribution Division, which supplies Menlo Park Municipal Water (2023–2026).
Total dissolved solids
24–320 ppm
Typical 320 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 and Sfpuc City Distribution Division, which supplies Menlo Park Municipal Water (2023–2025).
Who supplies Menlo Park, CA
California Water Service - Bear Gulch
Serves 52% of residents · Lake or river water · Chloramine
Menlo Park Municipal Water
Serves 48% 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.