Draining issue - from bad to worse

[Bodrey]

Hi All,

I was having a problem with my kitchen sinks draining properly. I realized that my pipe configuration was incorrect when I started looking up videos on YouTube, and that was likely contributing to the problem. So, I pulled it all out and re-configured it yesterday.

I just finished a load of dishes and expected the sink to drain quickly. Well, instead of the water draining (left sink) the water started backing up into the right sink until there was an even amount of water in the bottom of both sinks (3-4"). What gives... I am so confused right now. I don't understand why the problem has gotten worse, not better.

This is a pic of what my setup looks like...





Could I please have some plumbing pros provide some insight as to what the problem could be? TIA

[Alpha]

Hey, not a pro here but it looks like you have a vent pipe in the top left and what might be a garbage disposal unit, although I’m not completely sure. Since you mentioned that water is backing up evenly into both sinks, that usually means there’s a clog or restriction somewhere after the point where both drains join, so the water has nowhere to go and backs up into both sides. The problem could also be caused by the horizontal pipe connecting both drains not having enough slope. The slope is important because drain pipes need a slight downward angle to help water flow smoothly by gravity. If the pipe is flat or going uphill, water can get stuck or drain slowly causing backups. It might help to check the disposal for any jams, make sure the pipes have that slight downward slope, and look for any blockages in the trap or drain line. Also, if possible, confirm that the vent pipe is open and working properly. Hopefully, fixing these things will help your sinks drain better.

[Bodrey]

Alpha, I do have an ACC installed in the top left. However, I just installed that - the drainage issue was there prior to adding the ACC. I don't have a garbage disposal unit. I will definitely check the slope, but could that alone be capable of causing the sinks not to drain properly? I have a strong suspicion that the clog is further downstream. A poster on another forum also thinks this is the most likely case. I cleared out the P-trap when I rejigged the system. Next week, I plan to install a clean-out (to allow future access should the pipes become clogged again) and also auger it in both directions at the same time.

[Alpha]

Thanks for the update and clarification. Good to know the AAV was added later. You’re probably right that the clog is further downstream, especially since the P-trap is already clean. Water backing up evenly into both sinks usually points to a blockage past where the drains meet, likely in the pipe going into the wall or further down the line. While poor slope can slow drainage and contribute to buildup over time, a full backup like this is more often caused by an actual clog blocking the flow. Your plan to add a clean-out and auger in both directions sounds like a smart move and should help you locate and clear whatever’s causing the blockage. Hope it clears things up. Let us know how it goes!