Did you grow up hearing that we need to drink eight glasses of water a day? Drinking enough water is definitely important, but you can also overdo it in the water department. Overhydration – also called hyponatremia – occurs when we drink more water than our kidneys can process. The real tricky part is that the symptoms of overhydration are often similar to those of dehydration: fatigue, headache, and nausea. When we overhydrate, we throw the sodium levels in our blood out of whack, and that can cause serious long-term problems if we don’t do anything about it. Most people aren’t at risk for overhydration, but if you’re an endurance athlete or taking medicine that makes your mouth constantly feel dry, it’s something to keep in mind. Back when I was marathon training, I remember drinking water like it was my job. When you’re doing endurance training, you definitely need more water, but it’s also easy to overdo it. There are also medical conditions that can put you at risk for overhydration. Diabetes, congestive heart failure, or kidney problems can all cause excessive thirst. Avoiding Overhydration Here are some more tips for avoiding overhydration:

Don’t drink more than a liter (about four cups) of water per hour: That is a lot of water! Most of us need a lot less than that.
If you’re an endurance athlete, use a little science. Weigh yourself before and after your run, ride, or climb, then weigh yourself again afterwards. The difference is how much water you lost.
Drink water while you’re working out: Drinking a little water while you’re training can help prevent the insanely thirsty feeling that could cause you to overdo it after the fact.
Choose sports drinks (sometimes): Most exercisers don’t need sports drinks, but if you’re doing endurance training, these drinks provide electrolytes that you lose from those hours of sweating. They’ll help quench your thirst without causing you to overhydrate.
If you do feel like you’re constantly thirsty, you should absolutely talk to your doctor. You want to treat the underlying issue that’s causing you to drink too much.
How much water do I need? So, if eight glasses isn’t the answer, how do you know how much water you need? There are a couple of ways to tell!

Weigh yourself: Just like endurance runners, weight fluctuation can tell you about fluid loss. This seems like sort of an annoying way to monitor hydration, though. You’d need to weigh yourself frequently to get an idea of your hydration sweet spot.
Pee clear: pee to win. Your urine can tell you a lot about your health. If you’re properly hydrated, your urine should be pretty light or even clear. The only exception is “vitamin pee.” If your urine is bright yellow after taking your vitamins, don’t worry! That’s normal. If your pee is clear, chances are you are drinking enough water.
From what I’ve been reading on hydration, the key to staying hydrated without overhydration is just listening to your body. Like with everything else, moderation wins.

Basic truth.... Moderation wins!