Plumbing Tip: January 2015, Stop that running toilet
1. Identify the float ball and float arm inside the tank. This is the mechanism that shuts off the water. Once it floats to the correct level it will activate the shut-off.
2. With tank lid off, and while the toilet is filling after a flush, observe to make sure the float is reaching the proper height. If not, the toilet will continue to run, as the water will fall down the overflow tube.