Infiltration and Inflow, also known as I & I is when groundwater (infiltration) and stormwater (inflow) gets into the sanitary system. Infiltration typically occurs through holes, cracks, joint failures, and faulty connections in pipes or manholes because of age or disturbance. Because the City has separated stormwater and sewer systems, inflow typically occurs through illegal roof or foundation drain connections into the sewer system.
I & I is a problem because clean ground and stormwater gets into the sewer system, which means it must be treated along with sewer. It takes up capacity in the sewer pipes and the treatment is costly. Because of I & I, about three times the amount of wastewater is sent to the treatment plant in the winter than it does in the summer.
In order to address the issue, the City began a Sanitary Sewer I & I Repair program in 2018, which will continue into the future on an annual basis. The goal of this program is to repair and eliminate sources of I & I within the City.
Questions related to Infiltration and Inflow can be directed to the Operations Division at 360-342-5350.