Step 2 · Inspect Water Level and Identify Float

Look inside the tank to identify the cause of the running water. You will see a tall, vertical tube in the center; this is the overflow tube. Observe the water level. If it is high enough to be constantly spilling into the top of the overflow tube, the fill valve float is set too high. Also, identify your float type. Based on our assumed answer, you are looking for a 'float cup,' which is a cylindrical cup that wraps around the main shaft of the fill valve assembly (usually located on the left side of the tank).