Thank you for taking the time to reach out to us, we are here to help.
Yes, our Oral Care Liquid Solution can be used in a fountain, but if the fountain has a carbon filter we recommend removing it to allow our water treatment to get into the pets water dish.
When using our Liquid Solution in a fountain, we do recommend doing a thorough cleaning of the fountain at least once a week to keep all the components clean and sanitary.
Hope this helps, but if you have any other questions please let us know.