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Why Is My Sump Pump Running But Not Pumping Water?

Sump pump runs but moves no water? Diagnose clogged intake screen, airlock, or a jammed impeller and fix it quickly.

Category:Plumbing
Difficulty:Moderate
Time:30 min
Success:50%
Updated:Jul 29, 2026

quick_referenceQuick Answer

For Why Is My Sump Pump Running But Not Pumping Water?, start with "Unplug the Pump and Inspect Power": Turn off the breaker and unplug the pump. Verify the outlet is receiving power with a non-contact voltage tester. Ensure the float switch isn't stuck in the 'on' position. Stop DIY if water is actively flooding the basement. This is listed as a moderate recovery and usually takes about 30 min.

verifiedGuide Snapshot

Repair areaPlumbing
Estimated time30 min
DifficultyModerate
Stop conditions4

Last updated Jul 29, 2026. Review the stop conditions before continuing.

account_treeRecovery State

DeviceSump Pump
Current stateNo Discharge
Specific stateIntake Blockage
Failed stepWater Backing Up
Likely failure typeMechanical Jam
DIY boundaryDIY recovery first
paymentsCost decision

help1. Understand the Problem

A sump pump that hums without moving water often has an obstruction, airlock, or broken impeller. Debris can block the intake, a stuck check valve can trap air, or the impeller may be seized. Leaving it running dry can overheat the motor and cause permanent damage.

build_circle2. Try This First

Best First Step
Unplug the Pump and Inspect Power

Unplug the Pump and Inspect Power

Turn off the breaker and unplug the pump. Verify the outlet is receiving power with a non-contact voltage tester. Ensure the float switch isn't stuck in the 'on' position.

visibility3. Visual Guidance

See what's happening and how to try the first recovery step.

1
Clear the Intake Screen
Clear the Intake ScreenRemove the pump from the pit. Scrape off any debris, mud, or stones covering the bottom intake screen using a screwdriver or gloved fingers.
2
Check for Airlock
Check for AirlockLift the pump slightly and drill a small (1/8-inch) weep hole in the discharge pipe about 6 inches above the pump. This allows trapped air to escape.
3
Free the Impeller
Free the ImpellerRemove the bottom plate to access the impeller. Use pliers to gently turn the impeller shaft if it is seized. Look for broken vanes.
4
Reassemble and Test
Reassemble and TestReattach the cover, submerge the pump in a bucket of water (or the pit) and plug it in. The pump should eject water immediately after a short delay.

autorenew4. If That Doesn't Work

Try the next recovery options.

Try a quick airlock releaseIf the pump is airlocked, lifting the discharge pipe slightly to release the trapped air pocket can restore flow. Wear gloves and avoid shocking the pump.
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Clean intake screen from outsideIf accessible, use a garden hose to spray the outside intake while the pump is unplugged to dislodge debris without disassembly.
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Frequently Asked Questions

Why is my sump pump humming but not pumping?expand_more
Often a jammed impeller or clogged intake. Humming indicates the motor is getting power but can't spin the impeller.
Can a sump pump airlock be fixed without removing the pump?expand_more
Sometimes yes. Drill a small weep hole in the discharge pipe, or briefly lift the pump to break the air bubble.
How do I know if the impeller is broken?expand_more
Remove the bottom plate; if vanes are cracked or missing, replace the impeller kit.
Should I oil the impeller shaft?expand_more
No, submersible pumps are sealed. Oiling can attract dirt. Replace the pump if the shaft does not turn freely after cleaning.

warning5. Stop DIY If

Don't continue if any of these apply.

reportWater is actively flooding the basement
reportThe pump has a burnt electrical smell
reportYou see cracks in the pump housing
reportThe motor is scalding hot
Still stuck?Get personalized help with AI Recovery.

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This page provides general DIY guidance.
If you're unsure, it's always best to consult a professional.