Which issue can lead to excessive infiltration into a collection system?

Excessive infiltration into a collection system is primarily caused by structural failures or damages in the system itself. When there are cracks in pipes, groundwater can seep into the sewer lines, leading to increased inflow and potentially overwhelming the system's capacity. Cracks compromise the integrity of the pipes, allowing water to infiltrate where it shouldn't.

Other factors, while they may influence water levels or flow, do not directly cause infiltration as effectively as a compromised pipe structure. A high water table may contribute to some degree of groundwater presence but does not inherently create openings like cracks do. Inadequate maintenance often leads to deterioration but does not specifically address the immediate cause of infiltration itself. Low sewer flow might indicate less volume in the system, which might make infiltration seem less critical but does not contribute to the actual influx of external water. Thus, the presence of cracks in the pipes is the most direct cause of excessive infiltration.