Thanks for responding! Do you know if a carbon filter will affect the CS? I have a drinkwell fountain that the cats use and they also use Willow's water bowl. It's up on a stool so she can reach it more comfortably but they'll pull themselves up and drink from her bowl with their front paws resting on the stool, so I could put the CS in there too. About how much CS would go in the dog's waterbowl -- it's a big bowl and it gets changed daily to "freshen" it and defur it.