Definition - What does Infiltration mean?
Infiltration is the penetration of freshwater, or groundwater, into sewer systems through defects or damage in pipes or joints, manholes or inspection access points. Infiltration can also include an influx of flow from storm water runoff and ground water which enters sanitary sewer systems. Trenchless construction performs needed repairs and rehabilitative services to prevent or correct issues related to infiltration.
Trenchlesspedia explains Infiltration
Sanitary sewer systems aren't designed as storm drains for rain water or snowmelt. They move sewage through a network of pipelines to a treatment
facility where treatment then occurs. When excess groundwater flows
through manholes such as during a storm event, or
rainwater enters sanitary sewers, the costs of treating this excess water can raise treatment costs and environmental issues. There is also a danger of the excessive flow to cause the sewer to exceed its capacity which can trigger system failure.