Water is very important to the human body but why do we need it to live? We need water to live because it flushes all the toxins from our body and regulates our body temperature. Water is supposed to be very important to the human body and it is, but it can also be very bad. The reason water can be bad for the human body is if you drink too much of it. You can only go up to about three days without drinking water. A lot of people do not drink the right amount of water that they are supposed to drink in a day. The average amount of water needed a day is 9-13 cups for healthy men and women. It is important you drink the right amount, or you can pass out and start to feel dizzy.