Backups when washer drains

Quick Answer:

If water backs up when the washer empties during a spin, stop the machine and set it to drain slowly or use a manual drain setting. Check the standpipe and the washer’s lint trap or filters for buildup, run a controlled bucket test of the standpipe to see whether water overflows into other fixtures, and call a technician if the standpipe spills into toilets, tubs, or other living spaces.

Why This Happens

• Lint, fabric fibers and soap scum collect in the standpipe and the small trap or lint basket inside some washers, restricting flow.
• The washer drain often ties into a branch line shared by toilets, tubs or sinks. A partial clog downstream can push water into those fixtures when the washer pumps hard during a spin.
• Vent or slope problems in the drain system can make it harder for the washer’s fast discharge to move through the piping, causing backups.
• If you notice backups in more than one fixture at the same time, you could be dealing with Multiple drains clog suddenly from a shared drain or main line issue.

Step-by-Step What to Do

1. Stop the washer and set a slow drain

• Immediately stop the wash cycle. If your machine has a manual drain or a slow-drain setting, select that so the washer empties gently while you inspect the drain.
• Leaving the washer running at full pump while you troubleshoot increases the risk of overflow into other rooms.

2. Inspect the standpipe and remove any cover

• Look at the standpipe (the vertical pipe where the washer hose drains). Remove any plastic cover or cap and check for visible lint or debris at the top and inside the opening.
• Use gloves and a flashlight. Pull out lint by hand or with a long-handled brush; don’t force tools deep into the pipe.

3. Check the washer’s trap or lint basket and clean filters

• Many washers have a small lint basket or accessible filter near the pump. Follow the manufacturer’s instructions to access and clean it.
• Clean the washer’s inlet and pump filters if accessible. A clogged filter can slow draining and make the pump run harder.

4. Clear only accessible, non-invasive blockages

• If you can see and reach lint near the top of the standpipe, remove it. Don’t push a long wire or rigid tool into the standpipe; that can push a clog farther down.

5. Run a controlled bucket test

• With the standpipe open, slowly pour a 5–10 gallon bucket of water into it to simulate a drain discharge. Watch connected fixtures—toilets, tubs, sinks—for signs of overflow or backup.
• If the water flows down cleanly, the immediate clog may be in the washer or at the washer’s trap. If the water comes up in toilets or tubs, the clog is further down the branch or main drain.

6. If the standpipe overflows into toilets or tubs, stop

• If your test causes overflow into other fixtures, stop immediately and avoid running the washer again. This is a sign of a significant clog downstream that needs a professional.

What Not to Do

• Avoid using chemical drain-opening gels or caustic liquids in the washer standpipe—these chemicals can damage seals, rubber hoses, and internal pump components.
• Do not run multiple washer cycles to “flush” a suspected clog; that can push contaminated water into living spaces.
• Don’t poke blindly into the standpipe or plumbing with long metal rods that could damage piping or push a clog farther in.
• If water starts backing into other rooms or the standpipe consistently overflows during normal cycles, call a professional rather than continuing DIY attempts.

When to Call a Professional

• Water overflows into toilets, tubs, sinks, or other living spaces during the washer drain or during the bucket test.
• Multiple fixtures back up at once, or you smell sewage in the laundry area—these suggest a branch or main line clog.
• You can’t access or safely clear the clog, or the washer’s internal pump or hoses appear faulty.
• If you’re unsure how to reach internal filters or traps without voiding the washer warranty, contact a technician or appliance service.

Safety Notes

• Turn off the washer’s power before working near puddles or accessing internal components to avoid electric shock.
• Wear gloves and eye protection when handling dirty water or removing lint and debris.
• Avoid standing on wet floors or using extension cords in the laundry area while testing drains.
• If sewage is present, limit exposure and call a professional—raw sewage carries health risks.

Common Homeowner Questions

• Why does water come up in my toilet when the washer drains?
  Because the washer drain ties into a branch line; a downstream clog can force water into the toilet when the washer pumps rapidly.
• Can I snake the standpipe myself?
  A small hand auger can clear shallow, accessible blockages but avoid pushing tools into the washer connection; call a pro if the clog is deeper.
• Will slowing the spin speed prevent the problem?
  Slower draining can reduce the chance of immediate overflow, but it won’t remove a clog—inspect and clean the standpipe and filters or call a technician.

More in this topic

For more related fixes and similar symptoms, see Multiple Fixtures Backing Up Together.