Minecraft wiki entry for Water_gate, associated text: There are three parts to a water gate: The water source, the water channel, and the gate. The water source provides the water. The water source can be a lake, ocean, pond, or even just a water bucket dumped at the beginning of the channel. The channel is a small trench that guides the water where you want it to go. The gate itself is a device made of pistons that blocks the water flow.