How to Adjust a Float Valve
- 1). Remove the toilet tank cover. The float valve will typically be to the left of the overflow pipe.
- 2). Check the top of the float valve for the location of the adjustment screw and determine if it is a slotted-head screw or a Phillips-head screw.
- 3). Twist the float valve adjustment screw one full turn counter-clockwise to increase the level of water in the tank. Ideally, the float valve should be adjusted so it shuts the water supply off when the water level is about 1 inch below the top of the overflow pipe. Use the necessary incremental turns, more or less, as needed.
- 4). Twist the float valve adjustment screw one full turn clockwise to decrease the amount of water allowed to accumulate in the toilet tank. Make the necessary turns in the increments needed for proper toilet tank water level.
Source...