If you have not purchased a fountain for your pets to drink from, why not? Water circulation keeps the water at a cooler temperature, the filters ensure that hairs and other foreign materials are caught, and the charcoal keeps the water quality good for a long time.
I clean the fountains weekly to remove drool/slime from the plastic surfaces, but the filters every other week... Seven cats and one toy poodle enjoy drinking from the water spout directly, or the constantly circulating pool.
on January 15, 2013
We avoided replacing these just because we didn't think they were necessary, but we had to clean the fountain so often and it instantly would have build up in it. When we finally bought the filters, we realized how important they were and now our cat actually uses the fountain more too.