Why your bedside glass of water tastes "funny" come morning.

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Are you one of those people who religiously has a glass of water by your bedside every night?

Firstly, good on you. Not only are you ensuring you’re staying hydrated, but you’ve also eliminated the need to leave your cozy bed in the middle of the night to brave the freezing cold bathroom or kitchen. Clever.

But have you ever noticed that when your alarm goes off the next day and you take a sip from your glass, the water tastes a little “funny”?

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No, it’s not your imagination – you water really has changed. And while it’s not harmful, what’s happening will probably gross you out.

In a new video, Discovery News has explained the science of what’s going on in your glass while you sleep.

While it’s not exactly going off, the chemistry of the water is changing.

“By being exposed to air, the water absorbs some of the carbon dioxide and a tiny portion of that (about 0.13 per cent) is converted into carbonic acid,” they explain. (Post continues after gallery.)

“Some carbonic acid will then lose a proton or two, forming bicarbonate and carbonate respectively. This lowers the pH of water, making it slightly acidic and changing the taste.”

However this doesn’t necessarily mean it’s unsafe.

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“If you’re a human, the small shift in pH isn’t going to be what hurts you,” they reassuringly (kind of) say.

In fact, what you should be more concerned with is what’s going into your water.

“The problem is water in an unsealed container has been exposed to bacteria. Think about all the dust inside your house landing in your water!”

Right.

The good news is that it's not the end of the world. The DNews team advise filtering and boiling the water to make it good as new, or you could - you know - just pour it out (onto plants = clever you) and fill yourself a new glass.

However it's important to remember that it's not the water itself breaking down and going bad, it's just the other nastiness spoiling the taste.

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If you're really concerned, refresh your glass each night or consider making the switch to a sealed bottle - but remember even that has an expiry date (again for the plastic rather than the water inside).

Do you take a glass of water up with you each night? What are your tips for hydration?