InSinkErator
Shared Drain Line Restriction
Water backs up into the opposite sink bowl when disposal is running (on a double sink)
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Partial clog in common horizontal drain line, Improperly installed baffle tee or cross tube, Undersized or poorly sloped drain piping, Heavy food waste accumulation in branch line
How to Fix / Troubleshooting
Safety first: Turn off the disposal and do not use chemical drain cleaners.
- Check mechanical blockage: Remove the sink strainers and visually inspect both bowls for obvious obstructions.
- Clean the trap and tee: Place a bucket under the P-trap and baffle tee. Remove and clean them thoroughly, clearing any food buildup.
- Snake the line: If the trap and tee are clear, use a hand auger to snake the horizontal drain line in the wall from the trap arm.
- Verify piping configuration: Ensure the disposal discharges into a baffle tee designed for double sinks and that the non-disposal bowl connects properly to prevent backflow.
- Test: Reassemble, run water in both bowls, and operate the disposal to confirm proper drainage.
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Repair Difficulty
Medium
3/5
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