Herndon, VA tap water
Supplied mostly by Town of Herndon, 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 about 0.71 ppm of ammonia here. Some utilities switch to plain chlorine for a few weeks a year.
Safety for fish and shrimp
Ammonia (with conditioner)
Estimate0.12–1 ppm (Worth knowing)
Typical 0.71 ppm
This is what a conditioner frees when it breaks the chloramine apart. A cycled filter clears it within a day; a big water change in a new or very small tank adds more of it at once. Some conditioners also bind ammonia for a day or so.
Estimated from the chloramine level Fairfax Water reports (2024).
Nitrite (NO₂)
0.05 ppm (Low)
Essentially none, so any nitrite in your tank comes from the tank itself.
Published by your utility: Fairfax Water's 2024 water quality report.
Nitrate (NO₃)
Supplier's figure1–9.3 ppm (Low)
Typical 5.1 ppm
Water changes can't take your tank's nitrate below this level.
From the utility that supplies yours: Fairfax County Water Authority, which supplies Town of Herndon; Fairfax Water's 2024 water quality report.
Copper at home taps (first draw)
0.01–0.2 ppm (Low)
The 90th percentile of first-draw samples from homes: water that sat in household pipes for at least six hours.
Low. Water that sits in household pipes overnight can carry more than this.
Published by your utility: Fairfax Water's 2024 water quality report.
Chlorine or chloramine at the tap
0.5–4.1 ppm
Typical 2.9 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: Fairfax Water's 2024 water quality report.
Water chemistry
General hardness
Supplier's figure84–170 ppm
Typical 127 ppm
Moderately soft to medium. Suits most community fish and plants.
From the utility that supplies yours: Fairfax County Water Authority, which supplies Town of Herndon; Fairfax Water's website.
Carbonate hardness (alkalinity)
Supplier's figure54–88 ppm
Typical 77 ppm
Moderate buffering. pH should stay fairly steady.
From the utility that supplies yours: Fairfax County Water Authority, which supplies Town of Herndon; EPA monitoring data (2012–2019).
pH
Supplier's figure7.3–7.5
Typical 7.3
Most community fish do well here. Stable water matters more than the exact number.
From the utility that supplies yours: Fairfax County Water Authority, which supplies Town of Herndon; EPA monitoring data (2012–2019).
- Town of Herndon and Fairfax Water add phosphate to protect pipes. It can feed algae in tanks without much plant growth.
Who supplies Herndon, VA
Town of Herndon
Serves 83% of residents · Buys water from Fairfax County Water Authority · Chloramine
- 2024 water quality report
Fairfax Water
Serves 17% 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.
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Compiled by Shoal & Stem from public records. Free to cite with a link.