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Plumbing Re: Sink Drain

Want to know if it is an acceptable practice to allow bathroom sink drain to flow through floor (not wall) and splice into tub drain in basement which then leads to your main drain.  Contractor left me in a bind over shoddy work and had to let him go!  This was going to be his solution.  Wall drain is no longer an option.  Thank you!!  Rick

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Posted 2010-11-18T16:37:58+0000  by rickz42 rickz42

Hey rickz42.


Sorry to hear about the “contractor” there are a few of them out there.  Sorry it has taken so long with the answer, so I guess I am the one to tell you. I try to always teach best practices, therefore putting this drain through the floor is not recommended. I know, not the answer we were looking for, but the drain needs to be vented and it requires a P trap to keep odor and gases from coming back up the drain. It would also require a T in the main line with several reducers. This would also be a code inspectors worse nightmare.


I know you have been burnt once before, but I would recommend getting with a reputable plumber. They would know what is code or what is passable. Thanks for the question and I promise that the next question you have will be answered in a more timely fashion. is a great site to visit. It will tell you what contractors are good and which ones to avoid.

Posted 2010-11-21T14:41:08+0000  by Ingar_HD_ATL

Hey rickz42 Chris from the Atlanta Home Depot here, while not necessarily the best idea it is sometimes done when running a p-trap through the wall is not an option. You see this allot in older homes more than anything. Another option is to use an S-trap if space allows as this will let you still run the line into the floor and maintain an in-line trap. Looks like this:

Though depending on your area an S-trap may or may not be to code.  What is usually recommended in these dire situations is the use of an AAV (air admittance valve) under the sink. This gives you the benefit of having both a P-trap and a vent solution. But I can't stress this enough going by code is always the best bet and any plumber you get should be able to tell you which of these options is best for your situation.




Edit: Google search is the best! Here is a setup using an air admittance valve aav setup.jpg

Posted 2010-11-22T20:06:53+0000  by Chris_HD_ATL

The second diagram would be the preferred method if it were going to be inspected by a building inspector. The "S" trap is unacceptable.

Posted 2010-11-23T17:10:03+0000  by highinspect

Hello, I need a little assistance. Both sinks in my kitchen are clogged up. I've tried to plunge it and the water will go away, but the moment I remove the plunger, the sink fills right back up with water. The water won't even go down enough for me tom use some sort of drain unstopper. I also notice water coming while my dishwasher is running so I've stopped using it for now. Can you suggest something? Thanks

Posted 2011-01-07T15:05:10+0000  by TinzleyB

Hi TinzleyB, welcome back!

Plugged drains are no fun, but before you call a plumber I have a few ideas:


In my experience, I have always found that the kitchen drain clogs either in the horizontal pipe just past the p-trap, or at the elbow in the wall where the drain turns vertical.  I think it’s because this is the path where the water runs the slowest, and so muck tends to accumulate there.

Cleaning out drains is often a step by step process.  You try each method (easy ones first) until one of them works.  The first step (plunging) didn’t work, so on to the next one.


Under the sink, you will see the “trap”, a U shaped pipe that drain cleaner commercials often show full of gunk.  It will look something like this:


You will want to use a pair of slip-joint pliers to unscrew the nuts and remove this pipe.  Do the same for the pipe that heads into the wall. There’s a nut on the fitting right by the wall.

A project guide at also explains how to remove this: LINK.


Once removed, the sink should drain quickly out the end of this pipe, and into your bucket.

If you’re lucky, cleaning out the trap and wall pipe will clear the drain, and you can just put it back together.  Done!


If not, then the next step is to use a drain snake since you now have direct access to the plumbing inside your wall.  A snake in inexpensive, and looks like this:


Another project guide at shows how to use a snake: LINK.


At this point, you should now have cleared out the drain.

Put the trap back on and tighten the nuts.  Run hot water in the sink and check for leaks at the pipe connections.  Any leaks?  Try tightening the nuts a little.  If they still leak you will need to replace the washers.  Home Depot stocks these.  What you have just done is exactly the same thing a plumber would do if he/she came to your house.


You may have noticed that I have not recommended any chemical drain cleaners (yet).

This is because if the chemical does not work, then you have caustic liquids in the pipes just when you need to take them apart.  This is not a good thing.  Chemicals can help with slow drains, but don’t use them on stopped ones.  There are also enzyme based line cleaners that will help keep drains clear, but that’s another subject…

I hope this helps.  Please let us know if you have any questions.



Posted 2011-01-07T17:16:26+0000  by Chris_HD_CHI

Thanks Newf for your great advice. I'm happy to announce I plunged the left side first and also stuck a mechanism called the down my sink; (purchased from HD ofcoarse) I believe this loosend the clog because i plunged again and the right  sink water flow began to go down. I then poured the liquid drain product (also purchased from HD) down the sink. I noticed immediately the sink began to unclog. Yay!!! Thanks a bunch! And I didn't have to call the plumber!

Posted 2011-01-09T22:21:58+0000  by TinzleyB
Proves our old motto ... You can do it We can help

Ensures our new motto ... More Savings More Doing

You're empowered TinzleyB!
Posted 2015-11-05T19:46:06+0000  by Pat_HD_ATL
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