How does heavy rain affect the efficiency of waste water treatment?

Heavy rain can significantly reduce the efficiency of wastewater treatment systems by overwhelming their capacity. Increased inflow of stormwater can dilute the wastewater, making it more difficult to treat effectively. Additionally, excessive rainfall can lead to combined sewer overflows (CSOs), where untreated sewage is discharged into water bodies to prevent system backups. This not only compromises treatment efficiency but also poses environmental and public health risks.