Brentwood, CA tap water
Supplied mostly by Brentwood, 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 0.44 ppm of ammonia here. Some utilities switch to plain chlorine for a few weeks a year.
Safety for fish and shrimp
Ammonia (with conditioner)
Estimate0.49–1.58 ppm (Worth knowing)
Typical 1.17 ppm
About 0.73 ppm is already in the water, and a conditioner frees about 0.44 ppm more 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 Contra Costa Water District reports; Contra Costa Water District's 2025 water quality report.
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 22 ppm (Worth knowing)
Typical 22 ppm
High for tap water. Water changes can't take your tank's nitrate below this level.
From EPA monitoring data; Contra Costa Water District's 2025 water quality report (2014–2025).
Copper at home taps
Up to 0.11 ppm (Low)
Typically not detected
Not detected in testing. Water that sits in household pipes overnight can still pick some up.
From California Water Board lab results; Contra Costa Water District's 2025 water quality report (2024–2025).
Chlorine or chloramine at the tap
0–3.5 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: Contra Costa Water District's 2025 water quality report.
Water chemistry
General hardness
Supplier's figure52–116 ppm
Typical 56 ppm
Soft. Good for tetras, rasboras and most shrimp. Livebearers, snails and African cichlids prefer harder water.
From the utility that supplies yours: Ccwd/Brentwood WTP and Randall-Bold Water Treatment Plant, which supplies Brentwood; Contra Costa Water District's 2025 water quality report (2023–2025).
Carbonate hardness (alkalinity)
Supplier's figure44–82 ppm
Typical 53 ppm
Moderate buffering. pH should stay fairly steady.
From the utility that supplies yours: Ccwd/Brentwood WTP and Randall-Bold Water Treatment Plant, which supplies Brentwood; Contra Costa Water District's 2025 water quality report (2023–2025).
pH
Supplier's figure7.9–9
Typical 8.4
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From the utility that supplies yours: Ccwd/Brentwood WTP and Randall-Bold Water Treatment Plant, which supplies Brentwood; Contra Costa Water District's 2025 water quality report (2023–2025).
Total dissolved solids
Supplier's figure112–303 ppm
Typical 130 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 the utility that supplies yours: Ccwd/Brentwood WTP and Randall-Bold Water Treatment Plant, which supplies Brentwood; Contra Costa Water District's 2025 water quality report (2023–2025).
Who supplies Brentwood, CA
Brentwood
Serves 90% of residents · Buys water from Ccwd/Brentwood WTP · Chloramine
- 2025 water quality report
Contra Costa Water District
Serves 8% 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.