For all the hype surrounding status water bottles—looking at you, Stanley and Owala—it turns out many of us aren’t drinking nearly enough H2O. “It’s a struggle,” says Vanessa King, a registered dietitian nutritionist with Queen’s Health System in Oahu, Hawaii. “We see thousands of people a month, and drinking enough water comes up all the time.” Exactly how much you need to drink every day depends on a variety of factors, including your age, activity level, how much you sweat, and your health status, as well as which medications you take (some can cause dehydration) and your location (hot places call for more water).