Minecraft wiki entry for Egg_farming, associated text: For a fairly space efficient design, build walls around a 2x2x2 column. The bottom two spaces are the collection area (make sure to leave a door), and the upper of those has 4 signs to support the water. The next two layers are a water pool with no flow, especially not downwards. It's probably best to make the whole pool of source blocks. The chickens will go in and above the water—there should be a 1 or 2 tall gap above the water for the chickens to breathe in. The walls around and above the water should be glass blocks, to keep the chickens from suffocating each other against the walls.