You fill it with water, set it on the top of the cage(if it is screen) and let it drip through! You can put a small hole in the screen and feed the tube through. Let it drip on a branch or vine. If you don't want to use the tube you can set it on the screen top and let the spicket drip. Sometimes the water will pool if you do not poke a hole, so what I do is set it up on something a inch or so above the screen and the water will not pool on the screen top.