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

another comment talks about gases and whatnot but to add in : the water in a cup overnight stagnates and it’s not exactly “safe” or healthy to drink because of no water flow this allows bacteria to grow and multiply though very unlikely it’ll make you sick or unwell it’s still not clean water