Sump Pump Not Working — What to Check

A pump that hums but doesn't move water is almost always a stuck float or a jammed impeller.

Common causes

• Float switch stuck against the pit wall
• Jammed impeller from debris
• Failed check valve on the discharge
• Blown breaker or unplugged pump

Step-by-step

1. 01Confirm the pump is plugged in and the breaker is on
2. 02Lift the float manually — pump should kick on
3. 03Pour 5 gallons of water into the pit to trigger a normal cycle
4. 04Listen: humming with no water movement = jammed impeller

When to call Northbridge

• Pump is 7+ years old and cycling erratically
• Discharge water freezes at the exterior outlet in winter
• No battery backup and basement is finished
• Pit fills faster than a single pump can handle