Charter Oak, CA tap water
Supplied mostly by Three Valleys MWD, plus 2 other utilities. 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 a little ammonia. Some utilities switch to plain chlorine for a few weeks a year.
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)
Up to 26 ppm (Worth knowing)
Typical 11 ppm
Water changes can't take your tank's nitrate below this level.
From California Water Board lab results; Covina Valley Water Company - Wholesale and Three Valleys MWD, which supplies Covina-City, Water Dept. (2023–2026).
Copper at home taps
Up to 0.07 ppm (Low)
Typical 0.02 ppm
Low. Water that sits in household pipes overnight can carry more than this.
From California Water Board lab results (2023–2026).
Water chemistry
General hardness
85–280 ppm
Typical 109 ppm
Moderately soft to medium. Suits most community fish and plants.
From California Water Board lab results; Covina Valley Water Company - Wholesale and Three Valleys MWD and Walnut Valley Water District, which supplies Gswc-San Dimas; Covina Valley Water Company - Wholesale and Three Valleys MWD, which supplies Covina-City, Water Dept. (2023–2026).
Carbonate hardness (alkalinity)
72–220 ppm
Typical 97 ppm
Moderate buffering. pH should stay fairly steady.
From California Water Board lab results; Covina Valley Water Company - Wholesale and Three Valleys MWD and Walnut Valley Water District, which supplies Gswc-San Dimas; Covina Valley Water Company - Wholesale and Three Valleys MWD, which supplies Covina-City, Water Dept. (2023–2026).
pH
7.2–8.5
Typical 8.2
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From California Water Board lab results; EPA monitoring data; Covina Valley Water Company - Wholesale and Three Valleys MWD, which supplies Covina-City, Water Dept. (2013–2026).
Total dissolved solids
160–660 ppm
Typical 250 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; Covina Valley Water Company - Wholesale and Three Valleys MWD and Walnut Valley Water District, which supplies Gswc-San Dimas; Covina Valley Water Company - Wholesale and Three Valleys MWD, which supplies Covina-City, Water Dept. (2023–2026).
Who supplies Charter Oak, CA
Three Valleys MWD
Serves 46% of residents · Lake or river water · Chloramine
Gswc-San Dimas
Serves 46% of residents · Buys water from Covina Valley Water Company - Wholesale · Chloramine
Covina-City, Water Dept.
Serves 10% of residents · Buys water from Covina Valley Water Company - Wholesale · 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.
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Compiled by Shoal & Stem from public records. Free to cite with a link.