According to experts the body can become dehydrated without ever registering thirst. It's important to sip water throughout the day to avoid developing symptoms such as fatigue and body aches. To determine how much you should drink divide your weight (in pounds) by 2 - this is the amount of water (in ounces) that your body needs daily. For example, a 160 lb. woman should drink 80 oz. of water per day. When spending time outdoors, take mini breaks to drink in the shade. This will help cool the body and prevent sweating.