Sump pumps are routinely utilized in single-family residences and commercial establishments to pump stormwater and groundwater that accumulates around basement foundation walls and crawl spaces away from the affected structures. The city's stormwater utility and sewer user ordinances require sump pump discharge to be directed to the backyard of the property, nearby stormwater swale or sub-surface drain, retention pond, or stream.
Sump pumps may be accidentally or intentionally connected to the building lateral running to the sanitary sewer. These connections should be disconnected and re-routed to the stormwater system. To determine if you have an illegal connection to the sanitary, trace the sump pump discharge line while the sump pump running. If the pipe does not go outside to your yard, storm sewer, or into a cistern/dry well then it is most likely an illegal connection and needs to be disconnected from the sanitary line.