Why does water taste stale after sitting out overnight?

Question

I noticed that when I leave a glass of water on the bedside table, it taste pretty nasty in the morning. Why is that?

Answer 1

Best Answer - Chosen by Voters

when the water comes to your house from the water supply it is actually pressurized....it is also aerated, it is the air that gives it the 'fresh taste', when your water sits all night or day, it loses its 'air', also your water has a natural acidity that dissolves make natural CO2 (fizz) and it is largely due to the pH balance....so when it sits it loses its (fizz) due to the changing temperature (it is complicated actually to explain it)

Answer 2

its been oxidized how ever they say that when oxygen gets into it and makes it flat