El Rio, CA tap water
Supplied mostly by United Wtr Cons Dist, plus 4 other utilities. Here's what the water means for your fish.
Disinfectant
Chlorine or chloramine
Utilities here use chlorine or chloramine, depending on which one serves your address. Chlorine slowly gases off from standing water; chloramine doesn't.
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)
8–166 ppm (Worth knowing)
Typical 12 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; EPA monitoring data (2015–2026).
Copper at home taps
Up to 0.14 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 (2023–2026).
Water chemistry
General hardness
442–534 ppm
Typical 518 ppm
Hard. Ideal for livebearers and African cichlids. Soft-water species may struggle to breed.
From California Water Board lab results; California Water Board lab results, measured before treatment; United Wtr Cons Dist, which supplies Vineyard Ave Estates Mwc (2023–2026).
Carbonate hardness (alkalinity)
185–210 ppm
Typical 200 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; United Wtr Cons Dist, which supplies Vineyard Ave Estates Mwc (2023–2026).
pH
7.5–8
Typical 7.7
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; United Wtr Cons Dist, which supplies Vineyard Ave Estates Mwc (2023–2026).
Total dissolved solids
840–1030 ppm
Typical 960 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; United Wtr Cons Dist, which supplies Vineyard Ave Estates Mwc (2023–2026).
Who supplies El Rio, CA
United Wtr Cons Dist
Serves 58% of residents · Groundwater fed by surface water · Chloramine
Cal American Wc - Rio Plaza
Serves 20% of residents · Groundwater (wells) · Chlorine
Vineyard Ave Estates Mwc
Serves 12% of residents · Buys water from United Wtr Cons Dist · Chloramine
Cloverdale Mutual Water Co.
Serves 8% of residents · Groundwater (wells) · Chlorine
Vineyard Avenue Acres Mwc
Serves 8% 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.