Water level inside a toilet tank should be an inch below the top of the overflow tube. Higher water levels may lead to continuous flow of water hence wastage. Lower water levels causes poor flushing and may lead to clogging of the toilet.
The water level is controlled by a float ball. When the desired level is attained, the float ball rises and presses a cock that closes the inlet preventing more water from flowing into the tank. Water levels rising above the required level indicate that the screw holding the float ball is too tight hence preventing the ball from floating and closing the inlet. If the level is too low, the screw is too loose and hence the ball rises quickly and closes the inlet before there is enough water in the tank.
Depending on the situation, the screw should be adjusted to change the position of the float ball and attain the right water level. All you need is a screwdriver for tightening or loosening the screw. The adjustments made depend on the type of ball cock in your toilet.
Diaphragm and traditional plunger-valve ball cocks
These ball cocks are attached to a float ball through a float arm. Fold the arm upwards or downwards at the middle to raise or lower the water level respectively.
Floating-cup ball cock
Press the clip attached to the float cup and move it up or down to raise and lower the water level respectively.
Float-less ball cock
To decrease the water level, turn the screw in an anticlockwise direction. To increase the water level, turn the crew in a clockwise direction.
The float ball determines the water level inside the float tank. However, improper water levels may be caused by other defunct toilet parts including the handle. Therefore, be sure to check if all parts of the toilet are working properly before adjusting the float ball.