Why will water start to taste bad when you leave it in a glass for too long, but will taste fine when you dispense it out of a tap where it’s been sitting for months?

Question

If you leave water in a ceramic, glass, or cup it will start to taste bad after a day or two, even if it’s covered with a lid. However, when we pour water out of a tap into a glass it will taste fine, even though it’s been sitting for days/months in a water reserve tank. Why is this the case?

In: Other

Answer 1

Basically the water is flat. (Like a glass of soda vs a bottle). It can happen with water after its filtered too or when water is purified by Ozone (some say it tastes stale), but it’s just that the gasses have all left the water (generally bc it’s been still too long and doesn’t have an eco system to put gasses into it).

When water moves it gets a small amount out air mixed in. So if you have flat water from a filter or an old glass just pour the water between two cups (or shake in a bottle half full of air) some and you’ll taste an improvement.