San Lorenzo, CA tap water
Supplied mostly by East Bay Municipal Utility 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 about 0.58 ppm of ammonia here. Some utilities switch to plain chlorine for a few weeks a year.
Safety for fish and shrimp
Ammonia (with conditioner)
Estimate0.01–0.9 ppm (Worth knowing)
Typical 0.58 ppm
This is what a conditioner frees when it breaks the chloramine apart. A cycled filter clears it within a day; a big water change in a new or very small tank adds more of it at once. Some conditioners also bind ammonia for a day or so.
Estimated from the chloramine level East Bay Municipal Utility District reports; the chloramine level City of Hayward 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)
Up to 1.8 ppm (Low)
Typically not detected
Not detected in testing, so water changes lower your tank's nitrate well.
From California Water Board lab results; City of Hayward's 2025 water quality report (2023–2026).
Copper at home taps (first draw)
Up to 0.2 ppm (Worth knowing)
The 90th percentile of first-draw samples from homes: water that sat in household pipes for at least six hours.
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.
Published by your utility: East Bay Municipal Utility District's 2025 water quality report; City of Hayward's 2025 water quality report.
Chlorine or chloramine at the tap
0.1–3.7 ppm
Typical 2.4 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: East Bay Municipal Utility District's 2025 water quality report; City of Hayward's 2025 water quality report.
Water chemistry
General hardness
8–160 ppm
Typical 26 ppm
Soft. Good for tetras, rasboras and most shrimp. Livebearers, snails and African cichlids prefer harder water.
Published by your utility: East Bay Municipal Utility District's 2025 water quality report; City of Hayward's 2025 water quality report.
Carbonate hardness (alkalinity)
8–140 ppm
Typical 31 ppm
Little buffering. pH can drop quickly between water changes, especially with CO₂ or an older tank.
Published by your utility: East Bay Municipal Utility District's 2025 water quality report; City of Hayward's 2025 water quality report.
pH
8.2–9.5
Typical 9.3
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
Published by your utility: East Bay Municipal Utility District's 2025 water quality report; City of Hayward's 2025 water quality report.
Total dissolved solids
24–260 ppm
Typical 65 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: East Bay Municipal Utility District's 2025 water quality report; City of Hayward's 2025 water quality report.
Who supplies San Lorenzo, CA
- 2025 water quality report
East Bay Municipal Utility District
Serves 86% of residents · Lake or river water · Chloramine
- 2025 water quality report
City of Hayward
Serves 14% 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.
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.