It's time to deep-six the old advice to guzzle eight glasses of water a day. Your fluid needs fluctuate based on what you eat, whether you exercise, the medications you take, and your climate. A more reliable sign of healthy hydration: urine color. As long as it's clear or pale yellow, you're good.
Don't think twice about skipping ice. In one classic study, sippers most enjoyed H2O that was around 59°F—refreshing, but not cold enough to bring on brain freeze. Icy agua offers no advantage in cooling your core. (Sweat glands handle that job.)
Tap water in the United States is among the cleanest in the world. Still, impurities can trickle in. If your town's annual water quality report shows elevated levels of contaminants, try a filter. In many cases, a cheap carbon model that fits into a pitcher can remove them.
Sipping isn't the only way to wet your whistle. About 20 percent of the average person's water intake comes from food—and not just juicy produce such as cucumbers and watermelons. For example, cooked rice and white chicken meat both contain about 60 percent water. It all adds up!
Some brands of flavored water are loaded with more sugar per serving than a candy bar. Skip the liquid calories and add a refreshing twist of citrus to your glass.
Suspicious of seltzer? Don't be. Research has debunked the rumors that carbonated water erodes teeth and weakens bones. One caveat: Avoid fizzy drinks if you tend to get acid reflux.
Sources: Christine Gerbstadt, M.D., R.D., author of Doctor's Detox Diet (Nutronics); Barbara Rolls, Ph.D., author of The Ultimate Volumetrics Diet (William Morrow); Susan Yeargin, Ph.D., assistant professor of athletic training, University of South Carolina