Inflow and infiltration (I/I) is the excess flow of clear water into the City's sanitary sewer system:
- Inflow is when clear water from illegal connections of sump pumps, downspouts, and foundation drains is channeled directly into sanitary sewer pipes.
- Infiltration is when groundwater seeps into sewer pipes via cracks or leaky joints.
Because the sanitary sewer system was not designed to handle this excess clear water, it becomes overloaded during times of high groundwater or heavy rainfall. This can cause basement flooding or bypassing of raw wastewater to local streams and lakes.