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Fix a sump pump that makes noise

We'll help you identify whether the noise comes from the impeller, check valve, or loose mounting, then fix or replace the faulty part—or tell you when to call a pro.

Troubleshooting · Home plumbing
15–30 min
What you'll need
  • Screwdriver and wrench set
  • Replacement check valve (if faulty)
  • Pipe straps or clamps (if pipe is loose)
Diagnostic graph validation issues: Terminal node n_valve must have null branches; Terminal node n_impeller must have null branches
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Steps

Goal: Identify the noise source and fix the impeller, check valve, or mounting.

  • Listen when the pump runs and when it shuts off. Humming or grinding during run points to the impeller or motor. Rattling or thumping at shutoff points to the check valve. Vibration through the floor points to loose mounting.
  • Good: You can describe when the noise occurs. Proceed to Check mounting and discharge pipe.
  • Bad: The pump does not run at all—different problem (motor, switch). See When to get help.

Check mounting and discharge pipe

Goal: Rule out vibration from loose connections.

  • Inspect where the discharge pipe connects to the pump and where it is secured. Tighten loose clamps. Add pipe straps if the pipe is long and unsupported.
  • Good: Pipe is secure, vibration reduced. Proceed to Check check valve if you hear thumping at shutoff, or Check impeller if you hear grinding during run.
  • Bad: Still vibrating—check the impeller next.

Check check valve

Goal: Fix water hammer or rattling at shutoff.

  • Check the check valve on the discharge pipe. Confirm the arrow points away from the pump. Tighten fittings. Replace the valve if it is old or damaged.
  • Good: Quiet shutoff with no thump. The water hammer is resolved.
  • Bad: Still thumping—replace the valve or call a pro.

Check impeller

Goal: Clean debris or replace a damaged impeller.

  • Unplug the pump. Access the impeller area (remove the pump from the pit if needed, or lift a submersible to reach the intake). Clean debris from the screen and impeller. Inspect for cracks or wear. Replace if damaged.
  • Good: Pump runs quietly. No grinding.
  • Bad: Motor grinds or screeches—bearing failure. Call a plumber.

When to get help

Call a plumber if:

  • The pump does not run (motor or switch issue).
  • The motor makes grinding or screeching sounds (bearing failure).
  • You are not comfortable working in the sump pit.
  • You have tried cleaning and securing parts and the noise persists.

Verification

  • The pump runs and shuts off quietly with no thumping or grinding.
  • The discharge pipe is secure and does not vibrate.
  • The check valve closes properly and prevents water hammer.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm noise type Identify whether noise is during run, at shutoff, or both.
  2. Check mounting and discharge pipe Tighten loose connections and secure the pipe.
  3. Check check valve Tighten or replace the check valve if it causes water hammer.
  4. Check impeller Clean debris or replace a damaged impeller.
  5. Call a pro Motor bearing failure, deep pit work, or persistent noise—call a plumber.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Noise type (humming, grinding, thumping, rattling)
  • When noise occurs (during run, at shutoff, or both)
  • Check valve condition and orientation
  • Impeller condition (debris, damage)
  • Steps already tried

Does the pump run but make unusual noise?

Listen when the pump runs and when it shuts off. Identify whether the noise is humming, grinding, thumping, or rattling.

Pour water into the pit to trigger the pump. Listen during run and at shutoff. Good: pump runs but makes noise—proceed. Bad: pump does not run—different problem (motor, switch); call a pro.

Yes No

You can change your answer later.

Is the noise during run, at shutoff, or both?

Humming or grinding during run points to impeller or motor. Thumping at shutoff points to check valve. Vibration points to loose mounting.

Identify the noise. During run: check impeller and mounting. At shutoff: check check valve. Both: check all. Proceed to the matching section.

During run / vibration At shutoff / thumping

You can change your answer later.

Are the discharge pipe and mounting secure?

Loose clamps or unsupported pipe cause vibration. Tighten and add straps if needed.

Inspect discharge pipe connections and mounting. Tighten loose clamps. Add pipe straps if the pipe is long. Good: pipe is secure, vibration reduced. Bad: still noisy—check impeller.
Question

Are the discharge pipe and mounting secure?

Continue

You can change your answer later.

Is the check valve faulty or loose?

Water hammer at shutoff means the check valve is not closing properly. Check orientation and condition.

Check the check valve. Confirm arrow points away from pump. Tighten fittings. Replace if old or damaged. Good: quiet shutoff. Bad: still thumping—replace valve or call a pro.
Question

Is the check valve fixed?

Done

Is there debris or damage in the impeller?

Debris causes grinding. A damaged impeller causes uneven noise. Clean or replace.

Unplug the pump. Access the impeller area. Clean debris from the screen and impeller. Inspect for damage. Replace if damaged. Good: pump runs quietly. Bad: motor grinds or screeches—bearing failure; call a pro.
Question

Is the impeller clean and intact?

Done

Call a plumber

Call a plumber if the pump does not run, the motor grinds or screeches (bearing failure), you are not comfortable working in the sump pit, or you have tried cleaning and securing parts and the noise persists.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why does a sump pump make noise?
Common causes: debris in the impeller, a faulty or loose check valve (water hammer), or loose mounting or discharge pipe. Sediment or small objects can cause grinding or rattling; a bad check valve can thump when the pump shuts off.
Can I fix a noisy sump pump myself?
Yes, for many issues. You can clean the impeller, tighten or replace the check valve, and secure loose pipes. If the pump is submerged and you are not comfortable working in the pit, or if the motor itself is failing, call a plumber.
When should I call a plumber for a noisy sump pump?
Call a plumber if the motor makes grinding or screeching sounds (bearing failure), if you are not comfortable working in the sump pit, or if you have tried cleaning and securing parts and the noise persists.

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