Chicken watering cups and a automatic coop door are great. The watering cups can't handle hoise pressure though. I made a coffee can with a small float valve to act as a water tank. It gravity feeds to the cups and as it empties it refills itself, similar to a toilet tank.
Discussion
I've got the chicken cups but the ducks absolutely polite them so I can only have them in our chicken only zone. The coffee can float sounds really clever!!