Show All Answers

1. What is Inflow and Infiltration (I/I or I&I)

Inflow and Infiltration (I/I) is clear water originating from storm water runoff entering into the City's sanitary sewer system.

• Inflow is when clear water from illegal connections of sump pumps, downspouts, and foundation drains is channeled into the sanitary sewer pipes.


• Infiltration is when groundwater seeps or is directed into sewer pipes via cracks, leaky joints or connections.

2. Why is I/I a problem?

The excess clear water from I/I problems uses sanitary sewer capacity needed for wastewater. The result is sewer backups and increased costs for needlessly putting clear water through the wastewater treatment process.


The Metropolitan Council, which provides regional wastewater collection and treatment for the metropolitan area, requires communities with excess I/I to invest in local reduction remedies such as disconnecting sump pumps and foundation drains from sanitary sewers and repairing leaky sanitary sewer pipes. To urge compliance, the Metropolitan Council incorporated surcharges for communities with excess I/I. In 2015, the City of West St. Paul was faced with the choice of either paying a $2,709,950 surcharge (every time West St. Paul has excessive rainfall, it would be open to additional surcharges), alternatively West St. Paul was given the option to invest in an I/I compliance program that would eliminate the 2014 surcharge and prevent future surcharges.

3. Who is subject to an I/I Inspection?

All single-family owner occupied properties in West St. Paul must be inspected when properties are put up for sale and are required to be in compliance within 12 months after the sale of the property. Property owners are encouraged to get an inspection and come into compliance as soon as possible.


The City will conduct I/I inspections as part of its annual Pavement Management Program (PMP) the year prior to the street reconstruction.

4. What do I need to do for the inspection?

Schedule an inspection online here or by calling 651-552-4153. An adult must be present during the inspection. Clear a five-foot area around the vertical stack sewer clean out to give the inspector room to work. The inspector will televise your sanitary sewer service out to the City sewer main, check your sump pump discharge system, and check for roof drains/leaders.


The inspection involves televising the sanitary sewer service out of the City sewer main (to identify cracks and leaks) and checking the sump pump discharge system and roof drains and leaders (to identify improper connections to the sanitary sewer system).


Property owners will be given a copy of the inspection report which identifies specific areas of non-compliance and will include enough information to solicit bids for the repairs.

5. How do I know if I'm compliant?

For properties that pass inspection, the City issues a Certificate of I/I Compliance to the property owner and keeps a copy on file at City Hall. Certificates of I/I compliance will expire after ten years.


For properties that require repair work, a post-work inspection will be necessary and the City will issue a Certificate of I/I Compliance upon a successful re-inspection.

6. How long is an I/I Compliance Certificate good for?

Ten years. Inspections are not required if you sell your compliant property within that ten year period.