Kitchen Sink Gurgling and Backflow

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Old 01-14-21, 07:16 PM
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Kitchen Sink Gurgling and Backflow

Kitchen sink drain pipe gurgling while draining. Water backflowed from the red spot (pipe is for dishwasher and water filtration system drain lines) below every time I turned on the disposal. Have been very careful about what to drain through the sink. The pipe was snaked 6 months ago and now got clogged again which doesn't make sense to me. Accidentally removed the air admittance valve once but put it back. What might be the possible reasons? Any problems with the pipe design, especially the part circled in red? Thanks!

 

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01-14-21, 07:48 PM
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The red circled pipe is just plain wrong. It should be capped and abandoned or cut off left of the trap and replaced with a cleanout fitting. And your dishwasher should go to your disposal drain hookup which has a knockout which will need to be knocked out so that it can drain into a disposal. Then the disposal pipe should start low and then be looped up as high as possible before it comes down to the disposal.
 
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Old 01-14-21, 07:48 PM
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The red circled pipe is just plain wrong. It should be capped and abandoned or cut off left of the trap and replaced with a cleanout fitting. And your dishwasher should go to your disposal drain hookup which has a knockout which will need to be knocked out so that it can drain into a disposal. Then the disposal pipe should start low and then be looped up as high as possible before it comes down to the disposal.
 
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Old 01-15-21, 06:48 AM
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Also, the AAV should be located much higher. As high as it can go up near the bottom of the counter.
 
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Old 01-15-21, 08:46 AM
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True. I see now that your dishwasher goes to an air gap. If that is code for your area you can leave the dishwasher hose connected to it, but the other side should go to the disposal. The way it is plumbed may not be "wrong" since it works, but it is certainly unusual and could lead to an overflow if your pipes backed up while the dishwasher was running.
 
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Old 01-15-21, 10:48 AM
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Any chance that the gurgling sound you are hearing is from the RO filter system back washing?
 
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Old 01-16-21, 10:23 AM
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Any problems with the pipe design,
Yep, it's bad and not properly vented. AAVs are not a universally accepted cure all for a lack of a vent and not even allowed in many areas. I believe they have a place in some renovations where it isn't possible to get a vent outside in some older homes, but generally they should be avoided. They are definitely not a replacement for a proper vent.
 
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Old 01-18-21, 11:06 PM
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True. I see now that your dishwasher goes to an air gap. If that is code for your area you can leave the dishwasher hose connected to it, but the other side should go to the disposal. The way it is plumbed may not be "wrong" since it works, but it is certainly unusual and could lead to an overflow if your pipes backed up while the dishwasher was running.
Thanks for your reply! Actually my dishwasher does not have an air gap (if I'm correct). Here is another picture, just two draining lines (dishwasher and RO filter) into the Y-shape pipe.

 
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Old 01-18-21, 11:10 PM
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Any chance that the gurgling sound you are hearing is from the RO filter system back washing?
No, it's from the draining pipes but I cannot tell which section.
 
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Old 01-18-21, 11:15 PM
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Oh, yeah, that is so wrong. LOL
 
 

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