A sanitary sewer is a system of underground pipes designed to transport wastewater from homes, businesses, and industries to a treatment facility. This wastewater includes water from sinks, toilets, and showers, which is collected to prevent contamination of the environment and public health. The primary purpose of a sanitary sewer is to safely convey sewage away from populated areas. Once the wastewater reaches a treatment plant, it undergoes processes to remove harmful substances before being released back into the environment, often into rivers or oceans, ensuring clean water for ecosystems and communities.