East Palo Alto, CA tap water
Supplied mostly by City of East Palo Alto, plus 2 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 EPA monitoring data (2014).
Nitrate (NO₃)
Supplier's figureUp to 4 ppm (Low)
Typically not detected
Not detected in testing, so water changes lower your tank's nitrate well.
From the utility that supplies yours: San Francisco Regional Water System, which supplies City of East Palo Alto; EPA monitoring data; California Water Board lab results, measured before treatment (2014–2025).
Copper at home taps
Up to 0.17 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 (2023–2025).
Water chemistry
General hardness
Supplier's figure8–261 ppm
Typical 70 ppm
Soft. Good for tetras, rasboras and most shrimp. Livebearers, snails and African cichlids prefer harder water.
From the utility that supplies yours: San Francisco Regional Water System, which supplies City of East Palo Alto; California Water Board lab results, measured before treatment (2023–2025).
Carbonate hardness (alkalinity)
Supplier's figure8–232 ppm
Typical 84 ppm
Moderate buffering. pH should stay fairly steady.
From the utility that supplies yours: San Francisco Regional Water System, which supplies City of East Palo Alto; California Water Board lab results, measured before treatment; California Water Board lab results (2023–2025).
pH
Supplier's figure7.9–9
Typical 8.3
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From the utility that supplies yours: San Francisco Regional Water System, which supplies City of East Palo Alto; EPA monitoring data; California Water Board lab results (2012–2025).
Total dissolved solids
250–770 ppm
Typical 510 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 (2023–2025).
Who supplies East Palo Alto, CA
City of East Palo Alto
Serves 84% of residents · Buys water from San Francisco Regional Water System · Chloramine
Palo Alto Park Mutual Water Company
Serves 13% of residents · Groundwater (wells) · Chlorine
O'connor Tract Co-Operative Water Co.
Serves 7% 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.