Being mildly dehydrated is often the root of headaches, fatigue, constipation, dry eyes, among many other ailments. If you're feeling under the weather and otherwise healthy, ask yourself, when's the last time I drank a glass of water?

Consider NY Times personal health columnist Jane Brody's experience in her column, Dehydration: Risks and Myths:

"I dined out recently after an especially active day that included about five miles of walking, 40 minutes of lap swimming and a 90-minute museum visit. I drank only half a glass of water and no other beverage with my meal.

It did seem odd that I had no need to use the facilities afterward, not even after a long trip home. But I didn’t focus on why until the next day when, after a fitful night, I awoke exhausted, did another long walk and swim, and cycled to an appointment four miles away. I arrived parched, begging for water. After downing about 12 ounces, I was a new person. I no longer felt like a lead balloon.

Let’s start with some facts. Water is the single most important substance we consume. You can survive for about two months without food, but you would die in about seven days without water. Water makes up about 75 percent of an infant’s weight and 55 percent of an older person’s weight."

Dr. David Shute couldn't agree more. "Drink water and then drink more," he advises, because nearly all of us don't drink enough. A good indicator that you're well hydrated is that your urine is clear or light yellow.

"Good health is as close as your kitchen faucet, or the water fountain at work," adds Shute. "We're very fortunate, because Portland's drinking water quality ranks very high, thanks to Bull Run Reservoir and its source, Mt. Hood's snowpack.

So, when's the last time you drank a glass of water?