Bryn Mawr-Skyway, WA tap water
Supplied mostly by Skyway Water & Sewer, plus 2 other utilities. 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
Nitrite (NO₂)
Not detected (Low)
Not detected in testing, so any nitrite in your tank comes from the tank itself.
From EPA monitoring data (2012–2019).
Nitrate (NO₃)
Supplier's figureUp to 8.4 ppm (Low)
Typical 4.3 ppm
Low, so water changes lower your tank's nitrate well.
From the utility that supplies yours: Seattle Public Utilities and City of Renton, which supplies Skyway Water & Sewer; City of Renton's 2024 water quality report; EPA monitoring data (2012–2024).
Copper at home taps (first draw)
0.03–0.69 ppm (High)
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: City of Renton's 2024 water quality report.
Chlorine or chloramine at the tap
0–1.8 ppm
Typical 0.9 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 Renton's 2024 water quality report; Seattle Public Utilities' 2025 water quality report (2024–2025).
Water chemistry
General hardness
Supplier's figure25–125 ppm
Typical 47 ppm
Soft. Good for tetras, rasboras and most shrimp. Livebearers, snails and African cichlids prefer harder water.
From the utility that supplies yours: Seattle Public Utilities and City of Renton, which supplies Skyway Water & Sewer; City of Renton's 2024 water quality report; Seattle Public Utilities' website.
Carbonate hardness (alkalinity)
Supplier's figure23 ppm
Little buffering. pH can drop quickly between water changes, especially with CO₂ or an older tank.
From the utility that supplies yours: Seattle Public Utilities, which supplies Skyway Water & Sewer; Seattle Public Utilities' website.
pH
Supplier's figure7.4–8.5
Typical 8
Most community fish do well here. Stable water matters more than the exact number.
From the utility that supplies yours: Seattle Public Utilities and City of Renton, which supplies Skyway Water & Sewer; City of Renton's 2024 water quality report; Seattle Public Utilities' website.
Total dissolved solids
Supplier's figure36 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: Seattle Public Utilities, which supplies Skyway Water & Sewer; Seattle Public Utilities' website.
Who supplies Bryn Mawr-Skyway, WA
Skyway Water & Sewer
Serves 61% of residents · Buys water from Seattle Public Utilities · Chlorine
- 2024 water quality report
City of Renton
Serves 18% of residents · Groundwater (wells) · Chlorine
- 2025 water quality report
Seattle Public Utilities
Serves 15% 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.