Not 1596

A ballcock is a ball float on the end of a lever in the water closet of a toilet. As the level of water in the closet rises, so does the floating ballcock. When the water level is high enough, the lever operates a sliding valve and the water coming into the closet is shut off.

Just replace the ballcock valve..

A surge in water pressure can cause this. Also, a defective ballcock would pop off under these conditions. Replace the ballcock and consider installing a pressure reducing valve (PRV) on the incoming water line.

If you open the lid on your toilet you should see the ballcock. It is normally on the left side and has the float, that looks like a ball, attached to it. It is used to fill the water in the bowl and set the height of the water.