Seaside, CA tap water
Supplied mostly by Cal Am Water Company - Monterey, plus 2 other utilities. Here's what the 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 (2023–2025).
Nitrate (NO₃)
Up to 23 ppm (Worth knowing)
Typical 11 ppm
Water changes can't take your tank's nitrate below this level.
From California Water Board lab results; California Water Board lab results, measured before treatment (2023–2026).
Copper at home taps
0.11–0.38 ppm (Worth knowing)
Typical 0.38 ppm
Shrimp and snails are sensitive to copper. Water that sits in household pipes picks up the most; it drops once the tap has run for a minute.
From California Water Board lab results (2023–2025).
Water chemistry
General hardness
75–280 ppm
Typical 161 ppm
Moderately hard. Great for livebearers, and most community fish adapt.
From California Water Board lab results, measured before treatment (2023–2026).
Carbonate hardness (alkalinity)
66–180 ppm
Typical 144 ppm
Strong buffering. pH stays steady and hard to lower without RO water.
From California Water Board lab results; California Water Board lab results, measured before treatment (2023–2026).
pH
7.2–8.2
Typical 7.4
Most community fish do well here. Stable water matters more than the exact number.
From California Water Board lab results; California Water Board lab results, measured before treatment (2023–2026).
Total dissolved solids
106–620 ppm
Typical 106 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 (2023–2026).
- Cal Am Water Company - Monterey adds phosphate to protect pipes. It can feed algae in tanks without much plant growth.
Who supplies Seaside, CA
Cal Am Water Company - Monterey
Serves 70% of residents · Groundwater fed by surface water · Chlorine
Marina Coast Water District
Serves 25% of residents · Groundwater (wells) · Chlorine
Seaside Municipal Water System
Serves 7% 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.