In DIY circles, you may often hear the term "galvanized" in terms of piping or plumbing, gutters, roofing, and construction steel. Galvanization is a process of covering steel or iron with a zinc coating to prevent rusting. While galvanized metals will last years with their protective coating, they will deteriorate over time in acidic environments such as salt water marine locations and cold climates with salted roads. In terms of plumbing, galvanized pipes replaced cast iron and lead in the early 1900s, but have since been used mainly for outdoor applications because of their strength. Galvanized plumbing typically lasts about 70 years before it starts to rust from the inside out.