A cross connection happens when a sump pump is connected to a sanitary sewer line.  Often, this can be a hose leading into a laundry tub or a floor drain.  Sump pumps are supposed to drain into storm sewers, either through a direct connection (a pipe from the home connecting with the main storm sewer line), or by draining directly onto the ground through a pipe or hose outside the home.

Why are cross connections a problem?

Sump pump water is what engineers refer to as clear water, most often rainwater, ground water, or snow melt.  This water is clean enough to drain directly into area streams, ponds, and lakes without treatment.  Wastewater, water from your sinks, showers, tubs, toilets, and washing machines, must be treated at your area wastewater treatment plant before it can be safely discharged into the environment.