Most people leave a glass of water by their bed in case they get thirsty in the middle of the night, but is it safe to drink it in the morning when you wake up with a mouth drier than the Sahara?

It won't kill you, but it's not exactly the safest thing in the world.

When it comes to an open glass, you taking a drink and letting it sit out for 6-8 hours creates a petri dish of bacteria from your mouth. That bacteria combined with dust creates a film on top of the water.

As soon as your lips touch the glass and the water, there's bacteria multiplying like rabbits. The only thing working in your favor is that it's your own bacteria, so chances are there's just more of what was already in you.

Drinking someone else's overnight cup or water bottle could be a problem for you, their germs are going to multiply just the same, but enter your body. Their sick becomes your sick.

It's also not a good idea to drink that water bottle that's been rolling in your backseat all summer that you took one sip out of. Water doesn't necessarily expire, but sunlight makes bacteria grow even faster.

Read more at MSN

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