teh google search tips

water intoxication site:.edu
water intoxication site:.gov
water intoxication site:webmd.com

usually i find it easier to look it up in encyclopedia
and then follow up on the references

http://en.wikipedia.org/wiki/Water_intoxication

basically, liters of water, without electrolytes , bad for you

if its got flavor, its usually chock full of electrolytes

on a related note,
http://en.wikipedia.org/wiki/Oral_rehydration_therapy