What defines infiltration within the context of a wastewater collection system?

Infiltration in the context of a wastewater collection system specifically refers to groundwater entering the system through defects, such as cracks or joints in pipes. This concept is crucial because it identifies how external water can affect the capacity of a wastewater system, leading potentially to increased flow rates and the risk of system overflow or failure.

Understanding infiltration is essential for engineers and operators because they need to monitor and manage this groundwater intrusion to maintain the efficacy of wastewater treatment and prevent overloading the system. Addressing infiltration can involve repairing or replacing failing infrastructure to prevent groundwater from entering the system, thereby improving overall efficiency and reducing treatment costs.

The other options relate to types of water entering the system but do not accurately represent infiltration as defined in this context. Surface runoff, uncontrolled stormwater discharge, and excessive rainfall absorption pertain to different issues within stormwater management rather than infiltration of groundwater into wastewater systems.