Norwalk, CT tap water
Supplied mostly by South Norwalk Electric & Water, plus 1 other utility. 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)
0.7–6.9 ppm (Low)
Typical 0.7 ppm
Low, so water changes lower your tank's nitrate well.
From EPA monitoring data (2012–2019).
Chlorine or chloramine at the tap
0–0.6 ppm
Typical 0.4 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.
From EPA monitoring data (2019).
Water chemistry
General hardness
Not published yet
We haven't found this number yet. A drop test kit gives you your exact reading.
Carbonate hardness (alkalinity)
28–50 ppm
Typical 30 ppm
Little buffering. pH can drop quickly between water changes, especially with CO₂ or an older tank.
From EPA monitoring data, measured before treatment (2012–2019).
pH
7.1–7.6
Typical 7.2
Most community fish do well here. Stable water matters more than the exact number.
From EPA monitoring data (2017–2019).
- South Norwalk Electric & Water and Norwalk First Taxing District add phosphate to protect pipes. It can feed algae in tanks without much plant growth.
Who supplies Norwalk, CT
South Norwalk Electric & Water
Serves 48% of residents · Lake or river water · Chlorine
Norwalk First Taxing District
Serves 48% 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.