Q. I live in a six-unit condo building, there are six owners who each own an 80-gallon tank of a Vaughn Hydrastone lined electric water heater. I have lived in this building since it was built 20 years ago and the water heaters are still working well. I have heard that we need not replace our water heater because of the hydrastone lining. Some plumbers say to replace it. Do we need to think about replacing them in the very near future?