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Fix a grease trap that overflows

We'll confirm the symptom, check for clogs, then guide you to pumping and maintenance.

Troubleshooting · Home maintenance
20 min (checks) + pumping
What you'll need
  • Gloves and bag for waste (if cleaning small trap yourself)
  • Or contact for licensed pumper
Step 1 of 6

Quick triage — pick your path

Quick triage — pick your path

Choose the option that matches what you see. You can jump straight to that section.

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Steps

Goal: Confirm the symptom, check for clogs, then pump and maintain the grease trap.

  • Check if kitchen sinks drain slowly or if you see overflow from the grease trap. Grease and solids block flow when the trap is full.
  • Good: Slow drains or overflow—proceed to Check inlet and outlet.
  • Bad: No overflow—check other drains.

Check inlet and outlet

Goal: Rule out clogs before assuming the trap is full.

  • The inlet brings wastewater in; the outlet sends it out. A clogged outlet can cause overflow even if the trap is not full. Check accessible pipes for blockages.
  • Good: Outlet clear—proceed to Pump the trap.
  • Bad: Outlet clogged—call a plumber to snake the line.

Pump the trap

Goal: Empty grease and solids so the trap can function.

  • For small under-sink traps, remove the lid and scoop out grease and solids into a bag for disposal. For larger traps, schedule a licensed pumper.
  • Good: Trap emptied. Establish a pumping schedule.
  • Bad: Cannot access or pump—call a grease trap service.

When to get help

Call a plumber or grease trap service if:

  • Pumping does not resolve the overflow.
  • The outlet is clogged and needs snaking.
  • You have code compliance requirements.
  • The trap is in-ground or commercial.
  • You are not comfortable servicing it.

Verification

  • Trap pumped and flow restored.
  • No overflow or slow drains.
  • Pumping schedule established.
  • Grease and solids reduced going down the drain.

Escalation ladder

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

  1. Confirm symptom Check slow drains or overflow from the trap.
  2. Stop grease and solids Scrape plates, wipe grease—reduce what goes down the drain.
  3. Check inlet and outlet Rule out clogs before pumping.
  4. Pump the trap Empty grease and solids—self-service or licensed pumper.
  5. Call a pro Plumber or grease trap service for clogs, code compliance, or large traps.

What to capture if you need help

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

  • Trap type (under-sink or in-ground)
  • When trap was last pumped
  • Whether inlet and outlet are clear
  • Pumping schedule established

Do you have slow drains or overflow from the grease trap?

A full or clogged trap causes slow drains and overflow.

Check if kitchen sinks drain slowly or if you see overflow from the trap. Good: yes—trap may be full or outlet clogged. Bad: no—different issue.

Yes No

You can change your answer later.

Have you stopped putting grease down the drain?

Grease overloads the trap. Scrape plates and wipe pans before washing.

Stop putting grease and food solids down the drain. Scrape into trash. Good: grease reduced. Bad: continued grease—overflow will return.

Yes No

You can change your answer later.

Is the outlet clogged?

A clogged outlet causes overflow even if the trap is not full.

Check the outlet pipe. If water does not flow out after pumping, the outlet may be clogged. A plumber can snake it. Clogged: call plumber. Clear: pump the trap.

Yes No

You can change your answer later.

Pump the trap

Empty grease and solids. Small traps may be self-service; large traps need a pumper.

Pump or clean the trap. For under-sink traps, remove lid and scoop out grease. For in-ground or commercial, schedule a licensed pumper. Establish a pumping schedule.

Yes No

You can change your answer later.

Overflow resolved

Trap is pumped. Reduce grease going down the drain. Establish a pumping schedule. If overflow returns, call a plumber or grease trap service.

Done

Call a plumber or grease trap service

Call if: outlet is clogged, pumping did not help, you have code compliance needs, or the trap is in-ground or commercial. Do not delay—overflow can cause odors and code violations.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

How often should a grease trap be pumped?
Depends on size and use. Commercial kitchens may need pumping every 1–3 months. Home under-sink traps may need cleaning every few months to a year. A service can recommend a schedule.
What causes a grease trap to overflow?
Grease and solids accumulate faster than the trap can separate them. Lack of pumping, too much grease down the drain, or a clogged outlet can cause overflow.
Can I clean a grease trap myself?
Small under-sink traps can sometimes be cleaned by the owner. Larger in-ground or commercial traps require a licensed pumper. Check local codes—some jurisdictions require licensed service.
When should I call a plumber or grease trap service?
Call if: pumping does not resolve the overflow, the outlet is clogged, you have code compliance requirements, or the trap is too large to service yourself.

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