Welcome to the Official Website of Maple Plain Minnesota Maple Plain Minnesota

Inflow & Infiltration

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.

Inflow is by far the larger problem and occurs in direct proportion to rainfall. Inflow is usually traced to sump pumps (used by many homeowners to keep groundwater out of basements), roof downspouts and foundation drains that are connected to the City’s sanitary sewer system. Sump pumps are often connected to the sanitary sewer system via a hose leading from the sump to a laundry tub or a floor drain.

State law requires sump pumps, foundation drains and roof down spouts to be connected directly to a storm sewer or onto the ground, not to the sanitary sewer system.

Infiltration: Infiltration occurs when groundwater seeps into sewer pipes through cracks, leaky joints or deteriorated manholes

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