The short answer is yes, if you have a cat, you probably do need a cat fountain. But it’s not unequivocal. Does your cat seem to drink amply from his water bowl or have another source of running water? Is at least part of his diet comprised of wet or raw food? Does he appear healthy, is his skin elastic, his fur soft and shiny, his eyes bright and clear? Is he sprightly and as energetic as he should be for his age? If yes, then you probably do not need a cat fountain. But it still might be a good idea.