Petmate Deluxe Fresh Flow Cat Fountain

Buy Now
Pros: Small finches use it as a pool!
Cons: makes gurgle noise when a little under 1/2 full
At your cat's beck and call? get a cat fountain, this one was inexpensive works fine. Always used a filter.

the noise I found annoying but it's only when it's low on water so 'you know' to fill it.  Great for a couple of cats require something larger for multicat households. Overtime it was hard to find the filters, some people use fountains without filters if they don't have hard water.