How to Fix a Sump Pump That Won't Turn On

A sump pump that won't turn on is usually caused by power issues, a stuck float switch, or a clogged discharge pipe. Start by checking the power source and testing the float switch.

  1. Rule Out Power First. Start with the basics. Make sure the pump is plugged in securely and check if the outlet has power by testing it with another device. Look for any tripped circuit breakers in your electrical panel and reset them if needed. If you have a GFCI outlet, press the reset button. Power issues cause about 60% of sump pump failures.
  2. Lift the Float to Confirm. The float switch tells your pump when to turn on. Lift the float manually with your hand - the pump should start running when you raise it high enough. If it doesn't activate, the switch is likely stuck or broken. Clean around the float mechanism and remove any debris that might be preventing it from moving freely.
  3. Track Water to Exit. A clogged discharge pipe can prevent the pump from starting. Follow the pipe from your sump pump to where it exits your house. Look for ice blockages in winter, debris, or collapsed sections. Pour water into the sump pit - if water backs up quickly, you likely have a discharge problem that needs clearing.
  4. Clear the Impeller Completely. Unplug the pump and remove it from the pit. Look inside the pump housing for the impeller - this spinning part moves the water. Remove any debris, string, or small objects wrapped around it. Even a small obstruction can prevent the motor from starting. Clean the impeller thoroughly and make sure it spins freely by hand.
  5. Listen for Humming Motor. With the pump clean and reassembled, plug it back in and manually lift the float switch. If you hear humming but no water movement, the motor may be seized. Try gently tapping the motor housing with a screwdriver handle while lifting the float. If this doesn't work, the motor likely needs replacement.
  6. Confirm Installation Standards. Make sure your sump pump sits level on the bottom of the pit and isn't tilted. Check that the discharge pipe has a slight upward slope and includes a check valve to prevent water from flowing back into the pit. Poor installation can cause operational problems that seem like pump failure.