If you just poke a hole in the bottom of a barrel, the water will quickly run out at first and then slow right down or the hole will block and it will stop completely. We need something with even and very slow flow. There are several ways to achieve even flow but I am convinced that this method is the simplest and easiest and will prove to be the most reliable. You simply have a float in the water in the barrelm the float is attached to or is a container, there is a little hole in the container and there is a plastic tube leading from the float to an outlet from the barrel This means that the barrel will empty at a constant rate as the float simply drops as the water empties slowly from the barrel. The picture shows a float which is a glass pot lid. The water is leaking through the steam exit hole and the tube goes through the hole that I left when I removed the handle.