Sewer lines are so important to our health. They provide a safe route of disposal for all the waste that can cause an unhealthy situation to all of us if not working or installed correctly. Sewer line direct all the waster from your home or business to the city sewer where it is processed and disposed of safely. Sewer lines are laid in several different types of pipping. The most common pipping that you will have problems will be concrete, cast iron and sch. 35sdr (which looks like PVC but is much thinner) The replacements are generally done because of broken drain lines which is a result in the break down of the solidarity of the pipping. Sewer that are replaced today are replaced with sch. 40 PVC . This pipping is much ticker, stronger and will not corrode.