Water is essential to stay alive, there is no doubt about that. About 60 to 70 % of our body is water. Blood is mostly water and your muscles, lungs, brain and other organs need water to be able to function properly. Water helps to regulate your body temperature and water makes is possible to provide nutrients to your organs and tissues. Water also transports oxygen and removes waste. It also protects you joints and organs.
We lose water thru urination, respiration and by sweating. We lose more water when we are active. Alcohol and certain medication will also increase the amount of water your body loses.
If we lose water from our body and we don't replenish it we can get dehydrated. The symptom of dehydration is muscle and joint pain, lower back pain, headache and constipation. If your urine have a darker color and a strong odor, that's a sign that you are not drinking enough water.
If you are healthy you know when you have to drink water. Although some doctors say that you have to drink 6-8 glasses of water, there is no sense to "force" yourself to drink a lot of water. Many times water bottling companies want you to buy their product. Their claim that water cures or prevents illnesses and help you to lose weight are not well founded and often simply marketing gimmicks.
You don't always have to drink water to replace the water you lost from your body. At least 20 % of the water comes from the foods you eat. With soft drinks the problem is too much sugar and extra calories. Juices are good source with the added vitamins and sport drinks help keep your electrolytes in balance. Caffeinated beverages count too but too much caffeine is not necessarily good for you.