Castle Rock, CO tap water
Supplied by Town of Castle Rock. 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
Nitrite (NO₂)
Not detected (Low)
Not detected in testing, so any nitrite in your tank comes from the tank itself.
From EPA monitoring data (2013–2019).
Nitrate (NO₃)
Up to 0.9 ppm (Low)
Typically not detected
Not detected in testing, so water changes lower your tank's nitrate well.
From EPA monitoring data (2012–2019).
Copper at home taps (first draw)
0.01–0.84 ppm (Worth knowing)
The 90th percentile of first-draw samples from homes: water that sat in household pipes for at least six hours.
Shrimp and snails are sensitive to copper. Water that sits in household pipes picks up the most; it drops once the tap has run for a minute.
Published by your utility: Town of Castle Rock's 2024 water quality report.
Water chemistry
General hardness
67–239 ppm
Typical 121 ppm
Moderately soft to medium. Suits most community fish and plants.
Published by your utility: Town of Castle Rock's 2024 water quality report.
Carbonate hardness (alkalinity)
72–116 ppm
Typical 96 ppm
Moderate buffering. pH should stay fairly steady.
Published by your utility: Town of Castle Rock's 2024 water quality report.
pH
6.9–8.7
Typical 7.9
Most community fish do well here. Stable water matters more than the exact number.
Published by your utility: Town of Castle Rock's 2024 water quality report.
Total dissolved solids
156–486 ppm
Typical 248 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: Town of Castle Rock's 2024 water quality report.
- Town of Castle Rock adds phosphate to protect pipes. It can feed algae in tanks without much plant growth.
- Town of Castle Rock softens its water at the plant, so it may be softer than the local groundwater.
Who supplies Castle Rock, CO
- 2024 water quality report
Town of Castle Rock
Serves 92% of residents · Lake or river water · 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.
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.