Ask a GW Expert: How Should I Hydrate

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Most of us know that water is essential for life, but the specifics on how much water we should drink are less clear. What exactly does the body do with the water we drink? Quite a lot. Once absorbed and circulating in the bloodstream, water aids in important essential bodily functions, helping to transport nutrients, regulate body temperature through sweating, cushion joints, eliminate waste and toxins, transport nutrients and support nearly every chemical reaction in our cells. Simply put, hydration underpins survival and physical and mental performance.

But how much water is enough? The old "eight glasses a day" rule is more folklore than fact. The National Academies of Medicine suggest daily intake of about 3.7 liters (about 125 ounces) for men and 2.7 liters (about 91 ounces) for women, but that includes all fluids-even those from food. The truth is that your needs depend on your activity, environment and health. Thirst is a late warning sign, so it's smart to get ahead of it, especially during exercise, hot or humid weather, at high altitude, or during pregnancy, breastfeeding, or illness.

What about "special" waters-alkaline, mineral, distilled? Evidence shows little real advantage. Mineral water adds small amounts of calcium and magnesium, but you can easily get those from food. Alkaline water claims to balance acidity, yet your kidneys and lungs already handle that with precision. Distilled water just lacks minerals-hardly a concern if you have a normal diet. In short, these products are mostly about marketing, not science.

Bottom line: staying hydrated is what matters. Plain water remains the simplest, most effective and most affordable choice. Paying attention to your body's cues and increasing your intake during times of higher demand like exercise, heat, high altitude, pregnancy, breastfeeding or illness is the smartest way to support your health.

Richard Ricciardiis a professor and associate dean for clinical practice and community engagement at the George Washington University School of Nursing. Got a question you'd like answered by a GW faculty expert? Email gwtodaygwu[dot] edu(gwtoday[at]gwu[dot]edu)with the subject line "Ask a GW Expert" to learn more about (almost) anything.

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