They had it coming to them. I mean it's stupid to not check something out, if you are warned about something, maybe you should consider that they are right.
Information is so readily available on the net.
http://chemistry.about.com/cs/5/f/blwaterintox.htm
Can You Really Drink Too Much Water? In a word, yes. Drinking too much water can lead to a condition known as water intoxication and to a related problem resulting from the dilution of sodium in the body, hyponatremia. Water intoxication is most commonly seen in infants under six months of age and sometimes in athletes. A baby can get water intoxication as a result of drinking several bottles of water a day or from drinking infant formula that has been diluted too much. Athletes can also suffer from water intoxication. Athletes sweat heavily, losing both water and electrolytes. Water intoxication and hyponatremia result when a dehydrated person drinks too much water without the accompanying electrolytes.