Generally too much water is defined as water consumed above what the kidneys can process in an hour. Extremely healthy kidneys would be able to process about 30 ounces or approximately .9 liters of water in an hour. A person with kidney problems or with only one kidney should drink much less, as per doctor’s instructions. The person with healthy kidneys could develop water intoxication by drinking about 2 to 3 times what the kidneys can process. For a person with kidney problems or with one kidney, too much water might be defined as just an ounce or two over the recommended amounts in order to avoid that hazing incident in Chico, California last 2005.
For people with healthy kidneys it should be perfectly safe to drink two cups of water an hour, and for the dieter, even one cup an hour will fulfill requirements for getting plenty of water. However, drinking too much water in rapid succession can prove fatal and should definitely be avoided.