Gravity flow toilets tend to clean the bowl and wash down the bowl's walls during the flush, but may have poor rim wash-down. Before installing a low-flush toilet, check to make sure your present drain system is working and does not block easily. The toilet must have enough force and water to carry the flushed waste through the drain system. Ask about reported clogging problems. Cost and Savings Depending on existing water costs and availability in your area, water-saving toilets should eventually pay for your investment.
Most older toilets use three to seven gallons per flush.
To reduce the amount of water in the tank, displace some of the water. A plastic bottle filled with water would be one example. The object should not release or leak particles or materials into the tank. For example, bricks should not be placed in the tank unless they are contained with plastic bags or containers. The object should not interfere with any of the mechanisms or tank operation.