Minecraft wiki entry for Building_water_features, associated text: You can make the central column higher. No matter how high it is, the water will always flow into the trench at the bottom and will not spill out, if you have done it correctly. If you want a very tall fountain, consider making a 10 block tall column, or more. You can also expand the width as well as the height. Instead of making the frame 5 x 5, make it as big as you'd like. However, make sure that it is not any smaller than 5 x 5, or the water will flow onto the frame, and spill out.