Nothing in this world is perfectly safe. Even drinking too much water can kill you. Newspapers contain several sad accounts of people dying of water overdose, many of them a result of drinking competitions, extreme child discipline, or fad diets. For instance, Jennete Killpack was sent to prison for killing her daughter by forcing her to drink large amounts of water as a punishment. In a separate case, Jennifer Strange died of water overdose while participating in a water drinking contest sponsored by a local radio station. Drinking high levels of water leads to a potentially lethal condition known as "water intoxication" or "dilutional hyponatremia". In this condition, the excess water dilutes the sodium in the body down to dangerously low concentrations, leading the brain to take up water and swell to the point of failure. In this way, even a substance that is considered one of the least toxic in the world can kill you. The same concept applies to everything we eat, drink, breath, and touch. Even the oxygen we breath, which is essential to life, can cause intoxication and death when breathed at high pressure. Even water comes with a long list of potential side effects. You should never base a medical decision only on the existence of a list of side effects. Public Domain Image, source: Christopher S. Baird.