The sanitary sewer system of the city consists of main and lateral conduits of salt glazed vitrified earthenware, polyvinylchloride (PVC) plastic, concrete, or other similar pipe, with necessary accessories, and are designed to transport liquid waste materials. The sewers in the alleys or streets adjacent to the various lots are called main or lateral sewers. The sewers leading from the main or lateral sewers to the property on either side are called house sewers.