A sewer main is a large pipe that carries wastewater and sewage from homes and businesses to a treatment facility. It is a crucial part of a city's sanitation system, ensuring that waste is properly managed and does not contaminate the environment. These pipes are typically buried underground and can vary in size and material, often made of PVC, cast iron, or concrete. Regular maintenance is essential to prevent blockages and leaks, which can lead to serious health hazards and environmental issues.