If your pee is clear, you'll probably need to find a toilet soon, because you're over-hydrated.

The truth is, the body has a "thirst center" in the brain that helps regulate how much fluid we need, and it's impressively tuned (though it tends to become less effective as we move into old age). So the most important way to stay hydrated is to listen to your thirst and drink when you feel like it.

Don't ignore itchings for water or confuse them with hunger, and you'll generally be fine. And don't worry too much about the color of your urine, either. A light yellow or straw-like color can indicate you're well hydrated, but darker urine isn't necessarily a reason to panic.

"Dark pee might mean that you're running low on fluid, but it could also mean that your kidneys are keeping your plasma osmolality in check by conserving water," Aschwanden said.