When the tub on the second floor drains, my kitchen sink on my first floor overflows. They share the same air vent. Is there any way to modify the plumbing to stop this from happening? I can access the drain behind the kitchen sink drain from the garage. see attached pic of my house's plumbing. I do not have a basement. The drain from the kitchen sink goes to my clothes washer drain then out to the street.

 

Can you have the drain snaked down stream of the kitchen?

 

I agree with SDPlumber. You could re-pipe things to help with the back-up into the sink, but you'll still have an issue with a slow drain under the garage.

Get a plumber to snake the drain and maybe run a camera down it. Everything will run better with a clear pipe. Could be grease or kitchen gunk, or worst case, it could be a collapsed pipe or something. Either way, you'll want to know that it's draining correctly.

That should fix your overflowing problems.

 

Hi Thanks for the help. This seems to be an issue about once every 6 months. I could have the drain professionally snaked or do it myself. The end result is the drain always runs 75% better. I always tell my family members to drain the tub slowly (using the manual drain lever) but when someone forgets to do that, the kitchen overflows, not always but just when the drain is slow and the sink is full with dirty dishes.

I have a water alarm under the sink but it was in the wrong place at the time. I was not alerted of the problem until the water ran over the sink on the tile and under the carpet in the living room. I have fans pushing air underneath the carpet and pad and it usually takes days for it to dry out depending on how much water overflows.

It is overall frustrating but I guess it is common for homeowners to have water problems. I'll have to buy a snake to fix the drain. The last snake rusted out and had to be tossed. I typically buy the Rigid Power Spin with AUTOFEED for $50 at home depot. I connect a drill to it and run that through the kitchen drain. If you have any other suggestions, please let me know. I also put 1/2 cup baking soda, then 1/2 cup white vinegar, then a pot of boiling water down the drain to break up the gunk.

 

If the snake isn't working as well as you expect, you either need a snake with a larger head... or you have a problem with the pipes. There really should be no reason you need to snake it every 6 months unless you're dumping grease down the kitchen sink.

I'd suggest getting someone out with a camera to have a look at the pipe. Hopefully it just needs a good cleaning with a nice large-headed snake.