How to Repair a Float Cup Valve in a Toilet

A float cup valve is a common type of flush valve in toilets.

The valve consists of a tower on which a round plastic cup moves up and down. When the toilet is flushed, the drop in the water level causes the cup to drop, letting water flow into the tank. When the cup rises to the top, it shuts off the water. The main problem with float cup valves is that the cup sticks, causing the water to run constantly. Repairing the float cup valve requires ensuring that the float cup rides smoothly on the tower.

Remove the toilet tank lid and set it out of the way.

Turn the shutoff valve on the floor next to the toilet all the way to the right to stop the water supply to the toilet. Flush the toilet to remove most of the water in the tank.

Search for the float cup valve, which is on the left side of the toilet. Notice how the plastic cup is attached to the tower.

Apply plumber's grease with a cotton swab to the tower and the inside of the cup where the tower inserts into it. Move the cup up and down the tower to work in the grease.

Turn on the shutoff valve to supply water to the tank. Flush the toilet several times to ensure that the cup is working properly. Replace the tank lid.

Things You Will Need

  • Plumber's grease
  • Cotton swab

About the Author

Damon Koch has years of writing experience ranging from software manuals to song lyrics. His writing has appeared in software manuals for Human Arc and on the CDs "Small Craft Advisory" and "Impersonating Jesus." He also has worked in building maintenance since 2004. He has attended Lorain County Community College as well as Cleveland State University.