Why Is My Sump Pump Not Working?

A sump pump has four things that can go wrong: power, the float switch, the pump itself, and the discharge. Working through them in that order identifies the fault quickly.

It does nothing at all

Check the circuit and the outlet first, then the float. A pump that runs when the float is lifted by hand but not on its own has a switch problem, not a motor problem.

It hums but no water leaves the pit

The motor is powered but not moving water — commonly a blocked intake, a jammed impeller, an airlock, or an obstructed discharge line.

It starts and stops every few seconds

Short cycling usually means water is falling back into the pit because the check valve has failed, or the float is set too low for the pit.

It runs constantly

Either the pit genuinely keeps refilling, the float is stuck in the on position, or the water is being recirculated because the discharge outlet is blocked or drains back toward the foundation.