Half Moon Bay, CA tap water
Supplied by Coastside County Water District. Here's what its 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 (2023–2026).
Nitrate (NO₃)
0.2–1.8 ppm (Low)
Typical 1 ppm
Low, so water changes lower your tank's nitrate well.
From California Water Board lab results (2023–2026).
Copper at home taps
0.04 ppm (Low)
Low. Water that sits in household pipes overnight can carry more than this.
From California Water Board lab results (2024).
Water chemistry
General hardness
78–98 ppm
Typical 88 ppm
Moderately soft to medium. Suits most community fish and plants.
From California Water Board lab results (2023–2026).
Carbonate hardness (alkalinity)
85–86 ppm
Typical 85 ppm
Moderate buffering. pH should stay fairly steady.
From California Water Board lab results (2023–2026).
pH
8
Most community fish do well here. Stable water matters more than the exact number.
From California Water Board lab results (2023–2026).
Total dissolved solids
170–177 ppm
Typical 174 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 (2023–2026).
Who supplies Half Moon Bay, CA
Coastside County Water District
Serves all residents · Lake or river water · 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.