While taking showers conserves more water than filling up a bath tub, some days you just need to luxuriate in a hot bath. One way to save water is to simply displace the water with your own body weight as the water fills up. When the tub is about one-quarter of the way full, get in. As the water continues to rise around you, it'll get to the level you want while using less. Your body is taking up more room, which means the tub needs less water to fill up.