What causes infiltration in a sewer system?

Infiltration in a sewer system primarily occurs due to cracked pipes. When pipes are compromised—whether they have fissures, fractures, or other forms of damage—they allow groundwater to seep into the sewer system. This can lead to an increase in the volume of flow within the sewer, which can overwhelm treatment facilities and lead to further issues such as backups and overflows.

The physical integrity of the piping is crucial. Once cracks develop, they create a pathway for surrounding groundwater to enter the system. This infiltration is often more of a concern in older systems where the materials may have deteriorated over time.

Factors such as poor construction methods, high flow conditions, and excessive rainfall can exacerbate issues but do not directly cause infiltration. Poor construction may lead to pipe weaknesses, which could lead to cracks over time, while high flow conditions and excessive rainfall could influence the amount of water in the system but do not create the openings that allow for infiltration. Therefore, focusing on the structural integrity of the pipes highlights why cracked pipes are the primary cause of infiltration in sewer systems.