When you flush your toilet, water is released from the tank into the bowl. The force this generates carries away the sewage inside. If you need to give your toilet a flushing power boost, you should change the water level in the tank. To do so, simply adjust the fill valve, which fills your tank with water after a flush.
Lift off the toilet tank lid. On a dual-flush toilet, you may need to unscrew the flush button before you can remove the lid. Most buttons unscrew counterclockwise. Set the lid aside.
Check which type of float valve you have in your tank. Newer toilets have an integrated float valve, a ring-shaped device mounted around the fill valve. Older toilets have a ballcock, a large, ball-shaped device attached to the end of a rod that's mounted on top of the fill valve.
Turn off the water supply for the toilet. The water supply valve is mounted on the wall behind the toilet and will have a hose leading to the toilet tank. Rotate the knob on the end of the water supply valve clockwise to turn off the water.
Flush the toilet. Hold down the handle or the push button on top of the valve (for dual-flush toilets) until the water in the tank runs out.
Adjust the ballcock assembly by adjusting the screw that connects it to the fill valve. Turn the screw with a screwdriver to see which way the ballcock adjusts, as many models are different. If there is no screw, make the adjustment by bending the rod that attaches the ballcock to the fill valve.
Adjust an integrated fill valve by turning the adjustment screw located at the top of the fill valve, or pinching and sliding the float-adjustment coupling. The float-adjustment coupling attaches to a rail device on the side of the fill valve.
Flush the toilet. Check the water level. Make adjustments if necessary.
Replace the lid. Turn the water supply knob counterclockwise to restore water.