In the bathtub drain a plastic tube attached to a donut shaped reusable sponge filter draws the shower water up to a plastic 50 litre reservoir holding tank. Inside this tank is a black light to kill bacteria and a inline water pump energized by rechargeable batteries. Tank is equipped with a float shutoff. At the bottom drain in the tank is a plastic tube connected inside the toilet reservoir tank. City water line in is turned almost off in the event of an empty Smart Water Reservoir. Your shower water now is used to flush the toilet saving at least 5 flushes per day. That amounts to 25 litres of recovered water.