Haha we did have that problem for a while, but we just put the rocks in a big jug with water in and poured their water bowls from that - so they never saw the rocks. They are used to them now though so we just put them in the bowls.
we've been using dog rocks as well - i had been previously trying to follow her around with a watering can but as our garden is paddock sized it was quite a feat! no more burn patches over here and still a happy healthy excitable dog! :D