Lake St. Louis, MO tap water
Supplied by St Charles County Pwsd 2. Here's what its water means for your fish.
Disinfectant
Chloramine
Your water is treated with chloramine. Unlike chlorine, it doesn't gas off when water sits out, and many pitcher and fridge filters aren't rated to remove it. Conditioners that list chloramine on the label break it apart, which frees a little ammonia. Some utilities switch to plain chlorine for a few weeks a year.
Safety for fish and shrimp
Nitrate (NO₃)
Supplier's figure5.8–6.3 ppm (Low)
Typical 6 ppm
Water changes can't take your tank's nitrate below this level.
From the utility that supplies yours: St Louis City PWS, which supplies St Charles County Pwsd 2 (2012–2019).
Water chemistry
General hardness
142–184 ppm
Typical 163 ppm
Moderately hard. Great for livebearers, and most community fish adapt.
Published by your utility: St Charles County Pwsd 2's 2025 water quality report.
Carbonate hardness (alkalinity)
83–125 ppm
Typical 104 ppm
Moderate buffering. pH should stay fairly steady.
Published by your utility: St Charles County Pwsd 2's 2025 water quality report.
pH
8.3–9.1
Typical 8.7
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
Published by your utility: St Charles County Pwsd 2's 2025 water quality report.
Total dissolved solids
333–410 ppm
Typical 372 ppm
A rough measure of everything dissolved in the water. RO water reads near 0, so TDS is a quick way to compare waters.
Published by your utility: St Charles County Pwsd 2's 2025 water quality report.
- St Charles County Pwsd 2 softens its water at the plant, so it may be softer than the local groundwater.
Who supplies Lake St. Louis, MO
- 2025 water quality report
St Charles County Pwsd 2
Serves 92% of residents · Buys water from St Louis City PWS · Chloramine
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.
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Compiled by Shoal & Stem from public records. Free to cite with a link.