What is Infiltration/Inflow (I/I)?
Infiltration occurs when groundwater enters the sewer system through cracks, holes, faulty connections, or other openings. Inflow occurs when surface water such as storm water enters the sewer collection system through rain gutter connections, holes in manhole covers, illegal plumbing connections, or other defects. The sanitary sewer collection system and treatment plant have a maximum flow capacity of wastewater that can be handled. I/I, which is essentially clean water, takes up this capacity and can result in sewer overflows into streets and waterways, backups into homes, and unnecessary costs for treatment of this water. It can even lead to unnecessary expansion of the treatment plant to handle the extra capacity. Unless identified and corrected, these costs could get passed on to the consumer. How do we identify sources of I/I? A Sewer System Evaluation Survey (SSES) involves inspection of the sewer system using several methods to identify sources of I/I: • Visual inspection-acces
