Hydration prevents dehydration, cramps, fatigue, and heat stroke. Cold brew coffee is less dehydrating than hot coffee because it has less diuretic effect. Diuretics are substances that make you lose water from your body. Hot coffee has more diuretics than cold brew coffee because the high temperature extracts more oils and acids from the coffee beans. Plus, cold brew coffee tastes better than plain water, so you'll be more likely to drink enough of it.