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?

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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

23 Answers

Anonymous 0 Comments

Try this. Take old bad water and pour it from one glass to a different glass several times. Taste and enjoy.

Anonymous 0 Comments

Water sitting out is exposed to carbon dioxide which is absorbed into the water. Whereas water in pipes is essentially sealed off from this happening

Anonymous 0 Comments

Tap water has chlorine in it to help stop the germs from growing. Once water comes out of the tap the chlorine can leave the water over a day or so and the germs will start taking over.

Anonymous 0 Comments

I don’t know. I think this is a stagnant pond water scenario.
It isn’t circulating, dissolved gases are escaping, bacteria/yeast are landing in it. All of which may contribute to changing its “flavor”.

Also, I think that temperature is water’s flavor because it’s different from hot to cold.

Anonymous 0 Comments

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.

Anonymous 0 Comments

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

Anonymous 0 Comments

So when I keep water in my espresso maker tank and don’t use it for say a week, would the water taste bad?

Anonymous 0 Comments

Water that has been sitting in sunlight will begin to harbour algae and moulds after a period of time. It will take a while depending on how clean your water is to start with, also there is gasses, minerals and other things that fizz off as it sits there. For example if your water supplier uses chlorine (this makes little dust particles and ‘bits’ clump together and get picked up by the many filters) then the slight smell of swimming pool will slowly disappear and the small amount of chlorine turns to gas and floats away, it isn’t unsafe to drink it before this happens.

Used to work at a UK not for profit water supplier for Wales.

Anonymous 0 Comments

If you haven’t been home in a while you should always leave water running for a minute or two, especially in an older house.

Anonymous 0 Comments

And a more simpler answer is that water In a cup has been sitting in the open, exposed to everything in the air. Dusty wata.