We're always being told to drink more water, and for a very good reason. The human body without water is disastrous.
Your body is around 60% water, this keeps you all nice and squishy, as well as helping blood to flow and clearing dangerous toxins from the body.
As you become more and more dehydrated, cells begin to shrink as the body draws water from them to pump into the bloodstream. This, unfortunately, includes your brain cells, and when these shrink, it's very bad news.
This prevents them from operating normally, leading to confusion, delirium, headaches and ultimately coma and death as it becomes unable to sustain normal bodily function. As the brain physically shrinks in the skull, the blood vessels attaching it to the cranium can pull away, causing pain and bleeding.
One by one, your organs will begin to shut down. The kidneys will go first and, seeing as they are your body's filter system, this is bad news. Any waste products that are usually excreted in urine will remain in the body and levels will slowly rise, toxins will begin to build up in the blood and under the skin.
Muscles will cramp painfully and uncontrollably, and organs will begin to shut down as blood volume reduces. In some conditions, the process can last nearly two weeks.