A sump pump that stays silent while water rises in a St. Louis basement is alarming, but the cause is often simple. Work through the checks below in order, from the easiest to the most involved, and stop as soon as you find the problem.

Start with the power

Check the outlet the pump plugs into. If the outlet has a reset button, press it. Then look at the breaker panel for a tripped circuit. Storms and power flickers can trip a circuit that feeds the pump, and resetting it may be all that is needed. If the pump runs after a reset but trips again soon after, the circuit or the pump's motor may have a fault that needs a professional.

Unplug the pump before you reach into the pit, and keep the cord out of standing water.

Check the float

Most sump pumps start with a float, a buoyant part that rises with the water level and switches the motor on. With the pump plugged in, lift the float by hand. If the pump starts, the float and switch are working, and the problem is likely that the float is catching on the pit wall, a pipe, or the cord. If the float is stuck in the lowered position, check whether the cord is tangled, the float arm is bent, or debris is wedged underneath it.

Watch the float's path as it moves. A float that rubs against the side of the pit will not rise freely, and the pump will never receive the signal to start.

Look at the pit and the intake

Gravel, sand, and small debris settle into the pit over time and can block the pump's intake screen. Remove the cover, scoop out loose material, and inspect the openings at the bottom of the pump. Basements that have taken on water often leave grit behind, so the pit may need a thorough cleaning after any wet season.

Test the discharge line and check valve

If the pump runs but water does not leave the pit, the discharge line may be blocked or frozen, or the check valve may be stuck closed. Pour a pitcher of water into the pit while you watch the pump. If the float rises, the pump starts, and the water drains out through the discharge pipe, the system is working. If the pump hums without moving water, the impeller may be jammed or the intake may still be clogged, and the pump should be serviced.

Check the backup pump and alarm

Many St. Louis homes use a battery backup pump or a water alarm alongside the main pump. If the main pump has failed, the backup should take over, so check it too. Confirm the battery is charged, the backup float moves freely, and any alarm sounds when you test it. Write down the date of the last battery replacement so you do not have to guess later.

A quick checklist

  • Confirm the outlet has power and reset any tripped circuit.
  • Lift the float by hand and clear anything that blocks its travel.
  • Remove debris from the pit and the pump intake.
  • Test the discharge line by adding water and watching the pump respond.
  • Test the backup pump, its battery, and any alarm.

When to call a professional

Call a licensed plumber or sump pump service technician if the pump hums without moving water, runs constantly, trips the breaker again after a reset, or shows signs of electrical damage such as scorching or a burning smell. Those symptoms point to a motor, switch, or wiring problem that is better left to someone trained to repair it. Until help arrives, keep the pit clear and the cord dry, and avoid working in standing water near the pump.