Combined Sewers

Combined sewers are a type of drainage system designed to collect both sewage from homes and businesses, as well as stormwater from rain or snow, through a single pipe network. During dry weather, this system efficiently transports wastewater to treatment plants. However, during heavy rain or storms, the volume can exceed the system’s capacity, leading to overflow events where untreated mixture of sewage and stormwater is discharged into nearby water bodies. This design was common in older cities, but modern systems often use separate pipes for sewage and stormwater to prevent pollution and manage water more effectively.