Hot Water Pipe Leaks

In the past year, we have encountered at least 15 house in the Marietta, GA area with leaks on the copper piping below the slab. (Houses were over 25 years old) 14 out of 15 houses the leak was on the hot water piping. We have done some research and there are many different theories on the issue. Some plumbers suggest that old water heaters anode rods dissolve and there is not protection for the water heater or piping. One for definite reason hot water pipe failure is thermal expansion and contraction. Temperature changes on hot water lines may range from 50 degrees after a day of no use up to 120 degrees after using the hot water. Therefore the pipe flexes and may rub on rough objects in the soil. We have seen slab leaks on CPVC, Polybutylene, Copper, and PEX even within just years of new installation. Copper pipe still remains to be the most reliable piping for under slab applications.