Cartridge filters! The process of backwashing a pool wastes a LOT of water unnecessarily. So if you're committed to saving on your water bill (and the environment), consider switching to a cartridge filter system for your pool, as it eliminates the need for backwash. This pool filter also uses the least amount of energy and is the easiest to maintain. But it is also the most expensive. But between sand vs. DE filters, they both waste about the same amount of water.