By Heida Knapp Rinella

Eight, 8-ounce glasses.
Sixty-four ounces.
Two quarts.
A half-gallon.

Anyway you pour it, that's a lot of water.

Despite any punditry you may have heard lately that you really don't need to drink that much water each day, experts say you do -- especially in arid Southern Nevada.

"That's still published in our textbooks," said Susan Meacham, director of nutrition sciences at the University of Nevada, Las Vegas.

The recommendation, Meacham said, is based on a guideline of 1 milliliter of water for every calorie burned during the course of a day.

"For 2,000 calories that you're burning, you should be consuming 2,000 milliliters, which is about 2 liters, which is a little bit more than 2 quarts -- which is your eight glasses a day," she said.

Andreah Davi Werner, executive administrator of Weight Watchers of Southern Nevada and Southern Utah, said the group recommends -- "We never say in Weight Watchers that you have to do this or you have to do that" -- members drink six to eight 8-ounce glasses, which is why you'll often see Weight Watchers members carrying cups around.

Tom Higgins, a physician of emergency medicine and medical toxicology at University Medical Center, prefers not to set a concrete guideline, though he said the average person probably doesn't consume enough water.

"Just like everything else, there's never a completely simple answer," Higgins said. "It's tough to say in general everybody should drink eight glasses of water a day. The bottom line is you need to stay re-hydrated.

"Those of us who aren't acclimated to the heat, those of us who are working harder, should drink more."

And he has bad news for those who think they can just let their bodies tell them when they need to get some water:

"Once you become thirsty, you're already starting to get dehydrated."

"You really need to monitor your fluid consumption," Higgins said. A guideline for whether you're consuming enough water, he noted, is whether "you've urinated in the last several hours. That's one of the ways we tell in medicine if a person is dehydrated; we check to see if you're making urine. You need to go every two to three hours if you're exercising and working out; the average person, every three or four hours if they're just sitting around.

"If you're sweating profusely and working hard, drink fluids regularly before you start, and then every 20 to 30 minutes while you're performing the activity."

Meacham pointed out that the body of the average adult is 50 percent to 60 percent water; the bodies of infants are about 75 percent water.

"Of course, you reduce about 10 percent for obese people, about 20 percent for severely obese people, because fat displaces water," she said. "Women about 10 percent less, because of the body-fat difference."

Why is it so important to maintain the levels of water in our bodies?

"Because the functions of water are so important," Meacham said, "everything from maintaining temperature to distributing nutrients throughout the body to providing the shape and rigidity of our cells. It'll be a lubricant in our joints. Water actually functions as a cushion for body tissues.

"All the way around our organs and around every cell, there's a layer of fluid. A solvent to dissolve sugars in the bloodstream, digestive tract, saliva. It's a source of trace minerals."

Consuming too little water can cause big problems.

"Dehydration can cause everything from dizziness to lack of coherence," Meacham said. "Our thirst mechanism is very insensitive. By the time we decide it's time to stop and get a bottle of water, we're already approaching a level of dehydration that would be physiologically compromising."

The threat is most severe in infants and the elderly, she said, and is the primary cause of hospitalization among the elderly in Nevada.

Werner said dehydration can manifest itself in ways you may not notice.

"The days you feel flustered, the days you can't find anything, are probably days when you haven't had enough water," she said. "Clear water, clear mind and clear thoughts really do go together."

As for conventional wisdom that we get an ample supply of water from foods, Werner said, "I would highly disagree. There's also a high amount of sodium in food, so therefore it's absorbing it. But your body absolutely needs it."

And don't think that morning coffee or Coke will help much.

"When we're truly trying to take on water, water is really the best," Meacham said. "Tea and coffee, of course, contain caffeine, and caffeine is actually dehydrating. Alcohol is dehydrating.

"Orange juice is a wonderful food, extremely high in everything from folic acid to vitamin C to potassium; however, it's also very high in sugar. For true fluid replacement, we should dilute our standard orange juice 1 to 8. Sugar attracts water. When you put it in your gut, you will actually be pulling water out of your gut. Coca-Cola, Gatorade -- those are really high in sugar. They really must be diluted, some two times, some four times."

Werner said she's often asked by members if tea or Crystal Light will fill the bill.

"Are you going to take a shower in Crystal Light?" she asked. "Do you want to consider it water? What is this all about? If you really want to help yourself, give your body the optimum chance; give it the water it needs. Water is a great positive part of your body and your thought process."

Higgins said it is possible to drink too much water, which leads to psychogenic polydypsia, or water intoxication. "It's not that common in people who don't have mental illness or aren't actively trying to flush their systems."

Meacham said there are various reasons people don't drink enough water.

"I think particularly among the elderly, it's a matter of convenience," she said; many older people may have problems "moving around and getting rid of your water intake.

"Many of us are simply too busy; we don't take the time to consider our body needs.

"Availability; water is heavy to carry around."

But Werner said increasing water consumption often is simply a matter of retraining yourself.

"It's just a matter of getting accustomed to thinking, `Oh, I really feel like a glass of water,' " she said.

Increasing water consumption can help in weight control, she added.

"It's also necessary to learn, `Is my body really hungry or is my mind just thinking what I want?' " she said. "Water will help. Take a drink, wait 15 minutes, and you may be satiated and full. It lends to the fullness and it really helps your body."

Werner suggested adding fresh lemons to water to increase palatability, and placing filled cups or bottles in various locations that are part of your routine to increase convenience.