system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does tap water stay drinkable although it being in the pipes for weeks/days?
gpt
There is a small amount of disinfectant, chlorine or chloramine, put in the water.  This is enough to kill little things but not big things like you.  If you ever have delicate fish in a fish tank, you must remove the disinfectant or it will kill the fish.