Well here's how to make a Waterfall Bong, a close relative.
Construction is simple and quick.
Take a milk jug or a large empty soda bottle. If you really want to do it nice, use a glass jug. Put a bowl in the lid, just like a gravity bong. Instead of cutting off the bottom, cut a small hole in the bottom, about a half-inch wide. Put a piece of tape over the hole, or use a cork.