Gresham, OR tap water
Supplied mostly by City of Gresham, plus 1 other utility. 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 (2014–2019).
Nitrate (NO₃)
Supplier's figureUp to 0.5 ppm (Low)
Typical 0.1 ppm
Low, so water changes lower your tank's nitrate well.
From the utility that supplies yours: Portland Water Bureau and Rockwood PUD, which supplies City of Gresham; EPA monitoring data (2012–2025).
Water chemistry
General hardness
Supplier's figure7–80 ppm
Typical 9 ppm
Soft. Good for tetras, rasboras and most shrimp. Livebearers, snails and African cichlids prefer harder water.
From the utility that supplies yours: Portland Water Bureau, which supplies City of Gresham; Portland Water Bureau, which supplies Rockwood PUD (2025).
Carbonate hardness (alkalinity)
Supplier's figure25 ppm
Little buffering. pH can drop quickly between water changes, especially with CO₂ or an older tank.
From the utility that supplies yours: Portland Water Bureau, which supplies City of Gresham; Portland Water Bureau, which supplies Rockwood PUD.
pH
Supplier's figure8–9
Typical 8.5
Alkaline. Many utilities raise pH to protect pipes. Stability matters more than the exact number.
From the utility that supplies yours: Portland Water Bureau, which supplies City of Gresham; Portland Water Bureau, which supplies Rockwood PUD (2025).
Who supplies Gresham, OR
City of Gresham
Serves 66% of residents · Buys water from Portland Water Bureau · Chloramine
Rockwood PUD
Serves 34% of residents · Buys water from Portland Water Bureau · 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.