Galvanized steel was a popular choice for plumbing systems in the 20th century, but it’s fallen out of favour. Galvanized steel pipes are prone to rusting. If the pipes are really old, like pre-1960, they may have been treated with impure zinc, which can contain more lead than is advisable for a home plumbing system. Replacing galvanized steel with copper plumbing can increase the value of your home, and make it more attractive to home insurers. In fact, some insurers may ask you to replace your galvanized steel system before they will insure your home.