La Presa, CA tap water
Supplied mostly by San Diego County Water Authority, plus 3 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; EPA monitoring data (2012–2026).
Nitrate (NO₃)
Up to 28 ppm (Low)
Typical 0.5 ppm
Low, so water changes lower your tank's nitrate well.
From California Water Board lab results; Helix Water District and San Diego County Water Authority, which supplies Otay Water District; EPA monitoring data (2012–2026).
Copper at home taps
Up to 0.07 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
204–209 ppm
Typical 206 ppm
Moderately hard. Great for livebearers, and most community fish adapt.
From California Water Board lab results; Helix Water District and San Diego County Water Authority, which supplies Otay Water District (2023–2026).
Carbonate hardness (alkalinity)
105–119 ppm
Typical 112 ppm
Strong buffering. pH stays steady and hard to lower without RO water.
From California Water Board lab results; Helix Water District and San Diego County Water Authority, which supplies Otay Water District (2023–2026).
pH
7.9–8.1
Typical 8
Most community fish do well here. Stable water matters more than the exact number.
From California Water Board lab results; EPA monitoring data (2017–2026).
Total dissolved solids
460–520 ppm
Typical 490 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; Helix Water District and San Diego County Water Authority, which supplies Otay Water District (2023–2026).
Who supplies La Presa, CA
San Diego County Water Authority
Serves 30% of residents · Lake or river water · Chloramine
Otay Water District
Serves 30% of residents · Buys water from Helix Water District · Chloramine
- 2024 water quality report
Helix Water District
Serves 28% of residents · Lake or river water · Chloramine
Viejas Community System
Serves 12% 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.