Kitchen Drain Issue

Hi all,

New forum member hoping to get some help with a drain issue. My house is about 14 yrs old and has a septic tank. Bathrooms are on the side of the house nearest to the septic tank. No issues at all with toilets, shower drains or bathroom sink drains. Kitchen is on the other side of the house and the kitchen sink has an under-counter vent. About a week ago the kitchen drain started getting sluggish. Yesterday I removed the trap and ran a 50-foot snake down the drain. No blockage. I also went under the house and opened up a clean-out plug for a long section running across the house away from the kitchen. No issues at all. The snake was past the clean-out plug and I could see the 3" pipe was clear all the way to the other side of the house where drains are running fine. Next I removed the vent from under the kitchen counter and poured about 1.5 gallons down the drain as a test. It goes great at first then slows down and backs up and out the vent pipe. I figured the vent must be bad. Replaced it with a new vent today but it still won't flow if you pour 1.5 Gal into the sink. I can use a paper clip and open up the vent to allow some air in and the water will start to drain.

Thanks in advance
Mike

if it drains when you manually open the AAV, then it is the AAV
if you already replaced the AAV and it wont drain but will when you open the AAv manually
the aav you bought is no good
go get another one

Thanks, Frodo

If I hold the vent open for too long, water starts to come out of the vent. Is that a sign that there is back-pressure in the system for some reason?