We are purchasing a home in Maryland. The home was built in 1942. The current owner just purchased the home a year ago and in his inspection, there were no issues noted about the plumbing. Our inspector looked at the home this week and said that the plumbing throughout the house will need to be replaced. It is mostly galvanized plumbing with some copper pipes. He said that they did not use dielectric couplings between the galvanized and copper pipes, which is causing galvanic action. That galvanic action is happening throughout the house. All plumbing throughout the house will have to be replaced in 3-5 years.

The seller and his inspector from last year, argue that the plumbing is steel inside, which means the plumbing will not corrode inside...that the plumbing is fine the way it is. We're having a plumber look at the pipes and the seller is bringing in his own plumber.

Can you shed any expertise on this subject?