https://www.youtube.com/watch?v=y20oFRb8TiE It's cold outside. You aren't thirsty.  How much water should you drink? If you are not thirsty and feel tired, you may be dehydrated. If you have been drinking alcohol, you may also be dehydrated. Alcohol acts as a diuretic. Your body needs constant hydration to maintain proper bodily functions. The amount of fluid depends on your metabolism, the environment and your activity. Luckily, fluids come in many forms....