Just about everyone knows it's impossible to survive without water, but just how important is the wet stuff to our overall health?
For some answers, The Early Show turned to Samantha Heller, a nutritionist at the New York University Medical Center. For starters, co-anchor Harry Smith asked her how much water we should be drinking every day.
It used to be that eight glasses a day was the standard reply. But Heller said there are new recommendations by the National Academy of Science: about 91 ounces for women and about 125 ounces for men, which works out to a little more than a couple of liters.
It's also recommended that we drink when we are thirsty, throughout the day.
Why is it so important to drink the right amount of water?
Said Heller, "Everything in your body happens in a water medium. Your body is mostly water. All the chemical processes that happen in your body happen in water. So, if you don't have enough water all your system, all your functions will decline. We don't want that to happen. It moistens your eyes, mouth, nasal passages, your skin -- it is essential for life."
If, like Harry, you are thinking you have not been drinking enough water, remember that you also can get fluids in other ways: from vegetables, fruits, soups, even coffee, soda and juice, although caffeinated drinks work a bit against the process of hydration.
"But included in your day, it's fine," Heller said.
As for water sources, tap water is assumed to be safe. But Heller said if you live in an area where you are concerned about the water supply, it's not a bad idea to get it tested for things like lead, nitrates and micro-organisms.
You can get a filter for the tap in your home, and contact a local expert to figure out what you need to do in order to test your water. It's especially important for infants, pregnant women and those who have weak immune systems.