Infiltration/ Inflow (I/I) can be defined as the process by which storm water or ground water enter into the sanitary sewer system. Sewer system is designed to carry waste water from toilets, bathrooms, sinks, etc. in homes and offices to the sewage treatment plant. The sewer system is designed with estimated load capacity that it can carry. I/I can cause overloading of the sewer system, consequently causing backups, and overflow during heavy rain. Storm water drains are separate from sewer drains, and when storm water begins to empty into a sewer system, the amount of waste water emptied into the treatment plant exceeds the limit it can handle thus reducing its efficiency.
Trenchlesspedia Explains Infiltration/Inflow
Inflow is caused by improper connections added to the sewer system from groundwater sump pumps, foundation drains, and downspouts. This water is generally discharged into the ground or into a drainage ditch. Infiltration is caused by groundwater that seeps into the sewer system from cracks and leaks in the pipe. Groundwater does not belong in the sewer system and will only increase its load. Similarly, storm water drains also should not be connected to the sewer system. To prevent I/I, illegal or improper connections should be notified or rectified. Regular checks of pipe interiors can help detect pipe defects like cracks, corrosion, illegal joints, etc. Trenchless rehabilitation methods like CIPP, sliplining, mechanical spot repair, pipe bursting etc. are some of the methods that can be used to prevent I/I.