Rohnert Park's sewer system has two primary functions: First, collect the City's wastewater, and second, transport it for treatment to the Santa Rosa Subregional Water Reclamation System of Santa Rosa. The City's sanitary sewer system facilities include 100 miles of gravity sewers, 7.5 miles of sewer force mains, 16 inverted siphons, and 3 pump stations. The majority of facilities were installed between 1956 and 1980. The collection system's underground network of pipes range in size from 6 to 42 inches in diameter.