San Diego, CA tap water
Supplied by City of San Diego Public Utilities Department. Here's what its 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 about 0.43 ppm of ammonia here. Some utilities switch to plain chlorine for a few weeks a year.
Safety for fish and shrimp
Ammonia (with conditioner)
EstimateUp to 0.92 ppm (Low)
Typical 0.43 ppm
This is what a conditioner frees when it breaks the chloramine apart. A cycled filter clears it within a day.
Estimated from the chloramine level City of San Diego Public Utilities Department reports (2025).
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)
Not detected (Low)
Not detected in testing, so water changes lower your tank's nitrate well.
From California Water Board lab results (2023–2026).
Copper at home taps (first draw)
0.01 ppm (Low)
The 90th percentile of first-draw samples from homes: water that sat in household pipes for at least six hours.
Low. Water that sits in household pipes overnight can carry more than this.
Published by your utility: City of San Diego Public Utilities Department's 2025 water quality report.
Chlorine or chloramine at the tap
0–3.8 ppm
Typical 1.8 ppm
At tap levels, chlorine and chloramine are toxic to fish, shrimp and the bacteria in a filter. Water conditioners are made for this range.
Published by your utility: City of San Diego Public Utilities Department's 2025 water quality report.
Water chemistry
General hardness
54–285 ppm
Typical 237 ppm
Hard. Ideal for livebearers and African cichlids. Soft-water species may struggle to breed.
Published by your utility: City of San Diego Public Utilities Department's 2025 water quality report.
Carbonate hardness (alkalinity)
46–155 ppm
Typical 110 ppm
Strong buffering. pH stays steady and hard to lower without RO water.
Published by your utility: City of San Diego Public Utilities Department's 2025 water quality report.
pH
7.4–9
Typical 8.3
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
Published by your utility: City of San Diego Public Utilities Department's 2025 water quality report.
Total dissolved solids
105–634 ppm
Typical 532 ppm
A rough measure of everything dissolved in the water. RO water reads near 0, so TDS is a quick way to compare waters.
Published by your utility: City of San Diego Public Utilities Department's 2025 water quality report.
Who supplies San Diego, CA
- 2025 water quality report
City of San Diego Public Utilities Department
Serves 93% of residents · Lake or river water · 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.
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.