We have a powder room on the main floor with a toilet that has a sluggish flush. It's not clogged. While investigating the issue I discovered that neither the toilet nor sink in the powder room is vented (the full bathroom on the second floor is vented).

When I remove the powder room's sink from its waste pipe, and attempt to use that as an air vent for the toilet, the toilet flushes perfectly.

What are some permanent fixes to this problem?

  • 2
    An air-admittance-valve could work for you.
    – brhans
    Dec 5, 2016 at 16:18

1 Answer 1


A one way AAV (air admittance valve) can be installed in a vertical position above the sink to solve your problem, however, a minimum of one vent must be open to the atmosphere (outside the dwelling) to allow the release of pressure in the drainage system which may lead to sewer gases released into the home if not present.enter image description here

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