It comes as no surprise, then, that humans need it to survive. Considering that the majority of our body weight comes from water, not bones, muscle, or fat, it makes even more sense that we should drink enough on a daily basis to stay healthy, hydrated, and energized.

But when it comes to daily amounts of water, it’s not as easy to pin down how much you “need.” Of course, you can survive a few days without drinking any at all. But the more you go without it, the more your health deteriorates and the greater your chance is of dying. So what’s the amount we’ve got to strive to drink in a single day to keep our bodies hydrated and healthy? What is that specific amount we should hit?

Most experts have varying numbers depending on your height and weight and even your activity level. However, a lot agree that half a gallon a day (64 ounces, which is eight 8-ounce glasses) will suffice and put you in a very healthy category. At the very least, you’re drinking more water than the majority of Americans if you can squeeze in 64 ounces in a day.

The thing most fail to consider is how much water they’re actually consuming in a day. While going to the water fountain often during your youth got you a lot more water than you’d realize, that’s simply not the case anymore as you age. You’ve got to actively monitor how much you’re drinking in a day if you want to hit your daily quota. It’s almost to the point that you should have a glass of water at your side throughout your work day (if not some sort of bottle like a Nalgene or something) if you want to get in the ounces you need.

Of course, if you drink a lot less than 64 ounces in a day, you’re going to be just fine. I just can’t stress enough how much healthier you’ll feel if you drink that amount, though. You end up sleeping better. You end up thinking more clearly. You also curb your appetite more by drinking more water, which can help manage weight and your metabolism.

Water is, simply put, a necessity to our lives. If your health means something to you, don’t treat it as an option. Because it’s not.