We’ve used the Avalon fountain for years now and we and our pets love it. First of all, it can hold a few days worth of water, so you don’t have to worry as much about refilling the dog bowl. Second of all, inexpensive charcoal filters ensure that yuor pet is always drinking high quality water.
You have to wash it every couple of weeks, but the entire setup comes apart for easy cleanup. There are third party filters available as well to cut down on costs if you want them, bringing the price of each filter to about $1 each.