Generally, women need about 11.5 cups of water a day, and men 15.5 cups. But this doesn’t mean you should chug water. The water you get from other beverages, plus fruits and vegetables, counts, too. Before you reach for a sports drink, know this: You only need these sugary electrolyte beverages if you’re doing high-intensity exercise for an hour or more. For electrolytes without the sugar, drink coconut water instead.