Modesto, CA tap water
Supplied mostly by City of Modesto, plus 1 other utility. Here's what the water means for your fish.
Disinfectant
Chlorine
Your water is treated with chlorine. It slowly gases off from standing water, and any water conditioner removes it.
Safety for fish and shrimp
Ammonia
0.09 ppm (Low)
Ammonia in the water as delivered. A cycled filter clears it within a day.
From California Water Board lab results (2024–2025).
Nitrite (NO₂)
Not detected (Low)
Not detected in testing, so any nitrite in your tank comes from the tank itself.
From EPA monitoring data; California Water Board lab results (2012–2025).
Nitrate (NO₃)
Up to 44 ppm (Worth knowing)
Typical 18 ppm
Water changes can't take your tank's nitrate below this level.
From City of Modesto's 2024 water quality report; California Water Board lab results (2023–2025).
Copper at home taps (first draw)
Up to 0.06 ppm (Low)
The 90th percentile of first-draw samples from homes: water that sat in household pipes for at least six hours.
Low. Water that sits in household pipes overnight can carry more than this.
From City of Modesto's 2024 water quality report; California Water Board lab results (2023–2025).
Chlorine or chloramine at the tap
0–1.9 ppm
Typical 0.8 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: City of Modesto's 2024 water quality report.
Water chemistry
General hardness
32–304 ppm
Typical 185 ppm
Moderately hard. Great for livebearers, and most community fish adapt.
From City of Modesto's 2024 water quality report; California Water Board lab results (2023–2025).
Carbonate hardness (alkalinity)
Supplier's figure41 ppm
Moderate buffering. pH should stay fairly steady.
From the utility that supplies yours: Modesto Irrigation District, which supplies City of Modesto; California Water Board lab results (2023–2025).
pH
7.2–8
Typical 7.7
Most community fish do well here. Stable water matters more than the exact number.
From City of Modesto's 2024 water quality report; California Water Board lab results (2023–2025).
Total dissolved solids
29–1100 ppm
Typical 367 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 City of Modesto's 2024 water quality report; California Water Board lab results (2023–2025).
Who supplies Modesto, CA
- 2024 water quality report
City of Modesto
Serves 52% of residents · Buys water from Modesto Irrigation District · Chlorine
Modesto Irrigation District
Serves 47% of residents · Lake or river 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.