Centennial, CO tap water
Supplied mostly by East Cherry Creek Valley WSD, plus 3 other utilities. Here's what the 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 (2012–2015).
Nitrate (NO₃)
Up to 6.6 ppm (Low)
Typical 0.4 ppm
Low, so water changes lower your tank's nitrate well.
From EPA monitoring data; Denver Water Board, which supplies Southgate WSD; Denver Water Board, which supplies Willows WD (2012–2025).
Water chemistry
General hardness
Supplier's figure55–124 ppm
Typical 105 ppm
Moderately soft to medium. Suits most community fish and plants.
From the utility that supplies yours: Denver Water Board, which supplies East Cherry Creek Valley WSD; Denver Water Board, which supplies Southgate WSD; Denver Water Board, which supplies Willows WD (2025).
Carbonate hardness (alkalinity)
41–114 ppm
Typical 65 ppm
Moderate buffering. pH should stay fairly steady.
From EPA monitoring data; Denver Water Board, which supplies Southgate WSD; Denver Water Board, which supplies Willows WD (2017–2025).
pH
Supplier's figure8–8.3
Typical 8.1
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From the utility that supplies yours: City of Aurora, which supplies East Cherry Creek Valley WSD (2025).
Total dissolved solids
Supplier's figure98–273 ppm
Typical 220 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 the utility that supplies yours: Denver Water Board, which supplies East Cherry Creek Valley WSD; Denver Water Board, which supplies Southgate WSD; Denver Water Board, which supplies Willows WD (2025).
- East Cherry Creek Valley WSD, Southgate WSD, Willows WD and Arapahoe Cnty Wwwa add phosphate to protect pipes. It can feed algae in tanks without much plant growth.
- East Cherry Creek Valley WSD and Arapahoe Cnty Wwwa soften their water at the plant, so it may be softer than the local groundwater.
Who supplies Centennial, CO
East Cherry Creek Valley WSD
Serves 27% of residents · Buys water from Denver Water Board · Chloramine
Southgate WSD
Serves 25% of residents · Buys water from Denver Water Board · Chloramine
Willows WD
Serves 11% of residents · Buys water from Denver Water Board · Chloramine
Arapahoe Cnty Wwwa
Serves 6% of residents · Groundwater (wells) · 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.