A beer acts as a diuretic, and you actually lose water. But it doesn't take the place of those tall tumblers of cool, cool water. If you're thirsty, you may be dehydrated How much you actually need spurs debate. The traditional advice is eight 8-ounce glasses per day. But that formula is too simplistic, critics counter.
Sports equipment is another factor that comes into play.
But increased activity affects everyone's needs for water. In addition to influencing proper metabolism, water helps keep you cool. Temperature regulation in humans is dependent upon evaporation of perspiration on the skin. Insufficient fluids in the system hamper and slow the body's natural thermostat. Waiting to drink until you're parched is a big mistake.