I recently bought another unit, so now I have 2 units for the 5 cats we have. We ended up putting one on our sink in the bathroom, since some of the cats were determined to get fresh water from the tap when we were brushing our teeth.
One of the concerns I see stated from people, is how long the carbon filters last. I run my unit without the filter. The water flows much better and the foam filter around pump seems to do just fine, in catching all the debrie. I also only use bottled water or water from my sink reverse osmosis system, so I don't have to worry about carbon filtering the tap water, because I don't use tap water.