Macker, the water flushes the kidneys. You figure if a dog gets 32oz of water, that's 2lbs of water everyday. When the dog isn't working, he's laid up resting. The dog's body gets rid of the excess water throughout the day. You also have to take into account the body's ability to make metabolic water throughout the day from the processing of energy. So the kidneys are fine unless there is previous kidney damage.