For many years water lines were made of cast iron. Now people have realized that cast iron will corrode and allow this corrosion to enter the water as it passes through. For this reason many cities have eliminated the use of cast iron, and in city that still allow it, homeowners are choosing to replace them anyway due to health hazards. This is not a DIY project due to the heavy equipment that you will need. This short clip gives an overview of what to expect from the plumber when he does this job for you.