The Essential Nutrient Water is an essential nutrient for life. All living cells require it to function properly. Our bodies do not allow us to store or conserve water. It is used every day in helping the digestion and absorption of food, transporting nutrients and waste products in the blood stream, assisting with chemical reactions and circulation, promoting excretion, lubricating and cushioning the joints, and regulating the body's temperature.
Water also keeps our electrolytes in balance.
It is very important to be adequately hydrated for proper bodily functions. A diminished sensation for thirst naturally occurs as we age. Thus older adults can't rely solely on their sense of thirst but must force fluids. That answer depends on several things. Keep in mind caffeine and alcohol are diuretics and can interfere with hydration, causing your body to eliminate fluids.