I put my boys on royal canine and noticed their water consumption going up also. Actually I posted it on here too asking other members if they noticed that with their dogs. Due to her water consumption she has to pee a lot. Mine did too. I took them off of it, I found it to be way too expensive and putting a lot of weight of them.
Is your baby STARVING?? or is she begging?? She is a dog! dogs will eat & eat & eat & eat, til they puke it up pretty much! My boys can eat all their food and 2 mins later be begging me for my food. That does not mean they are hungry, it means they want MY food!
Id find out for sure if she has liver shunt before feeding her this special food. Try splitting her food into 2 portions and give her one portion in the morning and one in the evening. That may help.