Ejector Pump

An ejector pump sits in a sump or holding tank and uses an impeller to force wastewater upward against gravity when the tank reaches a set level. The pump activates via a float switch or pressure sensor and runs until the tank drains down. Unlike a grinder pump, a standard ejector pump does not break solids—it moves raw or mildly settled sewage, so the tank must be pumped regularly to avoid blockages in the discharge line.

These pumps are essential for basement bathrooms, wet bars, or any fixture below the main sewer or septic line. They're also common in commercial settings and new construction where the house sits lower than available gravity drainage. Discharge lines run uphill to the main drain, and a check valve is mandatory to prevent backflow. A vent line from the tank to daylight prevents vacuum lock.

Field reality: ejector pumps fail when tanks fill with roots, grease, or solid waste that the pump can't move. Size the pump discharge to the tank volume and fixture count—undersizing causes overflow and backups. Always install a backup power source if the system serves a primary bathroom; without it, you're looking at an emergency call at 2 a.m.