Why is inflow and infiltration (I/I) a concern in wastewater systems?

Inflow and infiltration (I/I) in wastewater systems refers to the unwanted water that enters the sewer system through various means, such as cracks in pipes, improper connections, or surface runoff. This is a significant concern for a few reasons.

Firstly, the influx of additional water increases the total volume of wastewater that treatment plants must handle. This can lead to treatment facilities becoming overwhelmed, especially during periods of heavy rainfall or snowmelt when I/I tends to increase. As a result, treatment costs escalate due to the need for increased capacity or additional processes to manage the larger volumes and associated contaminants.

Moreover, this excess inflow can exacerbate issues with sewer overflows. When the sewer system is unable to handle the volume of water due to I/I, it can result in backups, which may lead to untreated wastewater being discharged into the environment, creating public health hazards and environmental damage.

Overall, I/I is a concern in wastewater systems primarily because it not only raises operational treatment costs but also heightens the risk of overflows, making effective management of I/I a crucial aspect of maintaining wastewater infrastructure.