I was actually thinking something similar to the above mentioned gravity option. Even if there is a small amount of water in the bottom of the bowl, I think that proves to be better than having a bowl full of older water.
I have had automatic Waters in the past for smaller dogs, and I find that they still develop a residue over time because there is still a basin that water sits in and it is not completely flowing all the time.
I don’t doubt that any small water that doesn’t get automatically drained would evaporate, but I feel like being using gravity or solenoids or even the pump would work better as far as reducing overall amounts of water.
The Lixit I have seen before, but I’m not sure how it would work for several dogs, especially larger ones. I may look into that just to see how it works and the amount of water flow that comes out, but I have dogs that will drink half a gallon of water at a time when they have been running around and I don’t know that that little device would be adequate for their needs