Americans seem to carry bottled water everywhere they go these days. In fact, it has become the second most popular drink (behind soft drinks). But water lovers got a jolt recently when we heard that a new report had found that the benefits of drinking water may have been oversold. Apparently, the old suggestion to drink eight glasses a day was nothing more than a guideline, not based on scientific evidence.

"Think of water as a nutrient your body needs that is present in liquids, plain water, and foods. All of these are essential daily to replace the large amounts of water lost each day," says Joan Koelemay, RD, dietitian for the Beverage Institute, an industry group.

Kaiser Permanente nephrologist Steven Guest, MD, agrees: "Fluid losses occur continuously, from skin evaporation, breathing, urine, and stool, and these losses must be replaced daily for good health," he says.

When your water intake does not equal your output, you can become dehydrated. Fluid losses are accentuated in warmer climates, during strenuous exercise, in high altitudes, and in older adults, whose sense of thirst may not be as sharp.

Here are six reasons to make sure you're drinking enough water or other fluids every day:

1. Drinking Water Helps Maintain the Balance of Body Fluids. Your body is composed of about 60% water. The functions of these bodily fluids include digestion, absorption, circulation, creation of saliva, transportation of nutrients, and maintenance of body temperature.

"Through the posterior pituitary gland, your brain communicates with your kidneys and tells it how much water to excrete as urine or hold onto for reserves," says Guest, who is also an adjunct professor of medicine at Stanford University.

When you're low on fluids, the brain triggers the body's thirst mechanism. And unless you are taking medications that make you thirsty, Guest says, you should listen to those cues and get yourself a drink of water, juice, milk, coffee -- anything but alcohol.

"Alcohol interferes with the brain and kidney communication and causes excess excretion of fluids which can then lead to dehydration," he says.

2. Water Can Help Control Calories. For years, dieters have been drinking lots of water as a weight loss strategy. While water doesn't have any magical effect on weight loss, substituting it for higher calorie beverages can certainly help.

"What works with weight loss is if you choose water or a non-caloric beverage over a caloric beverage and/or eat a diet higher in water-rich foods that are healthier, more filling, and help you trim calorie intake," says Penn State researcher Barbara Rolls, PhD, author of