Why Does My Toilet Keep Filling Up Inside the Tank?

You hear the sound of water running inside your toilet bowl all hours of the day. The toilet is the largest source of water use in your home, and a constantly refilling toilet is the sound of money literally going down the drain. A leak causes the water level inside the drain to gradually but continuously drop.

Toilet leaks cause a tank to have to refill.

To compensate, the refill valve cuts on periodically to replenish lost water. Diagnosing the problem is the first step in determining a remedy.

Water on the Floor

Look for water on the floor, which may be symptomatic of a loose tank bolt, which anchors the toilet to the floor, or a worn gasket between the tank and the bowl. If the toilet only leaks after flushing, the gasket is the likely candidate and should be replaced immediately. If there is water on the floor but the source of the leak is not obvious, add food coloring into the bowl and wait a couple minutes before flushing. Look for the coloring around the base of the bowl to determine the source of the leak.

Refill Valve

The toilet refill valve shuts off once the water inside the tank reaches a certain level. If the refill valve float ball is adjusted incorrectly, water may rise as high as the overflow tube. The excess water drains into the overflow tube, but meanwhile the fill valve continues to run. Lift the tank lid and take a peek inside to determine whether water is draining into the overflow tube. A float attached to the fill valve determines when the valve shuts off. Gently bend the float arm down so that the water level rises no higher than 3/4 inch from the top of the overflow tube.

Flapper Valve

The flapper valve acts as a door for water exiting the tank. The flapper then seals off the tank, allowing water to fill the tank once again. A worn flapper will fail to form an effective seal against the valve seat, however. Water seeps around the edges of the flapper, causing the water level to dip and triggering the refill valve. Replace your worn flapper with an identical model to ensure compatibility.

Pull Chain

The pull chain is attached to both the pull handle and flapper valve. A short chain will prevent the flapper valve from dropping and forming a seal against the valve seat. A long chain can sometimes become caught between the flapper valve and valve seat. In either case, water flows steadily from the tank. Adjust the length of the chain so that the flapper valve lowers to the valve seat without becoming entangled.