From people using water in kitchens and bathrooms in their homes and from commercial and industrial use. Nearly half the state's population, over 2 million people in 43 communities, send sewage to MWRA's treatment plants on the shores of Boston Harbor. Over 5,500 businesses and industries contribute wastewater as well.
Sewage travels through three different sets of pipes.
Water that is used in a home or industry is flushed through a building's pipes until it reaches local sewers which are owned and operated by city and town sewer departments. These 5,400 miles of local sewers transport the wastewater into 228 miles of MWRA interceptor sewers. The interceptor sewers, ranging from 8 inches to 11 feet in diameter, carry the region's wastewater to two MWRA treatment plants. Though most of the wastewater flows by gravity some low-lying areas require pumping. At present, MWRA provides full primary and partial secondary treatment to its wastewater flows.