El Sobrante, CA tap water
Supplied mostly by Western MWD, plus 1 other utility. 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)
1.2–29 ppm (Low)
Typical 1.2 ppm
Low, so water changes lower your tank's nitrate well.
From California Water Board lab results; Riverside Public Utilities (RPU)'s 2025 water quality report (2025–2026).
Copper at home taps
0.02–0.8 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; Riverside Public Utilities (RPU)'s 2025 water quality report.
Chlorine or chloramine at the tap
0.1–0.8 ppm
Typical 0.6 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: Riverside Public Utilities (RPU)'s 2025 water quality report.
Water chemistry
General hardness
Supplier's figure8–570 ppm
Typical 197 ppm
Moderately hard. Great for livebearers, and most community fish adapt.
From the utility that supplies yours: Metropolitan Water Dist. of So. Cal. and City of Riverside and Eastern Municipal WD and Western MWD and Chino Basin Desalter Auth. - Desalter 2, which supplies Western MWD; Riverside Public Utilities (RPU)'s 2025 water quality report (2023–2026).
Carbonate hardness (alkalinity)
Supplier's figure9–360 ppm
Typical 133 ppm
Strong buffering. pH stays steady and hard to lower without RO water.
From the utility that supplies yours: Metropolitan Water Dist. of So. Cal. and City of Riverside and Eastern Municipal WD and Western MWD and Chino Basin Desalter Auth. - Desalter 2, which supplies Western MWD; Riverside Public Utilities (RPU)'s 2025 water quality report (2023–2026).
pH
7.4–8.5
Typical 8.5
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From California Water Board lab results; Riverside Public Utilities (RPU)'s 2025 water quality report (2025–2026).
Total dissolved solids
Supplier's figure27–1150 ppm
Typical 357 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: Metropolitan Water Dist. of So. Cal. and City of Riverside and Eastern Municipal WD and Western MWD and Chino Basin Desalter Auth. - Desalter 2, which supplies Western MWD; Riverside Public Utilities (RPU)'s 2025 water quality report (2023–2026).
- Western MWD adds phosphate to protect pipes. It can feed algae in tanks without much plant growth.
Who supplies El Sobrante, CA
Western MWD
Serves 72% of residents · Buys water from Metropolitan Water Dist. of So. Cal. · Chloramine
- 2025 water quality report
Riverside Public Utilities (RPU)
Serves 34% of residents · Groundwater fed by surface water · 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.