Your sewer line is responsible for transporting waste from your home to the main sewer under the street. Gravity is the main force behind your sewer system, allowing wastewater to flow downhill and through a long series of pipes. The wastewater first moves to the main waste and vent stack, which then curves to the sewer line, and finally exits via the sewer line near the foundation of your home.
Sewer lines can be composed of either clay or PVC piping. Clay sewer pipes can last for 50 to 60 years and were the most popular choice for homeowners up until 1980 when PVC (polyvinyl chloride) piping was introduced to the market. PVC piping can last over 100 years, but like most things, both types of piping will eventually wear out.