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Installing A Bathroom Sink P Trap Drain With Zero Clearance Below The Wall Drain Pipe Connection PVC

NOTE: It's been brought to my attention that the solution presented in the video is actually an S trap that could potentially allow the water in the trap to be sucked out and sewer gas to pass through. I'm not a certified plumber. Please consult a plumber for your plumbing repairs. This video is just to document the solution implemented to my plumbing problem, and it may not be the correct way to do it.

There are 2 solutions to modify the S trap shown into a P trap.

1. Use an Air Admittance Valve at the top horizontal section (between the P trap and the vertical PVC where the water descends).

2. Extend the top horizontal section to at least 2X the P trap diameter (P trap diameter is 1.25in so a 2.5+in horizontal length would work). This effectively converts an S trap into a P trap. The solution shown in the video has at least 2.5" of horizontal section, but I may want to increase that to prevent any problems.

The new bathroom vanity we installed has a fixed shelf that is directly below the drainpipe in the wall. Therefore the P trap can not be installed in its regular location (such that it hangs below the wall drain).

Parts used for the connection:

- P Trap Kit, includes the marvel to PVC adapter -

- 90 Degree 1-1/2in PVC Connector - - Buy 1 of these if you have copper drain pipe at the wall. Buy 2 of these if you have PVC drain pipe at the wall.

- 90 Degree 1-1/2in PVC Connector Spigot x Socket- - This is for the lower connection to the wall drain if you have copper drain pipe. You do not need this if you have a PVC wall drain pipe.

- Short Length of 1 1/2in PVC Pipe -

- PVC Cement Glue -

- Hacksaw to cut the p trap kit and PVC pipes to length -

I tried an off the shelf solution, Snappy Trap, which has a flexible tube after the P trap. Although the Snappytrap bridged the connection between the sink drain and wall drain, it applied so much force that it created stress in the sink drain that could cause leaks in the future. In general, it's not a good idea to apply continuous bending stress to plastics.

Here's a link to the SnappyTrap. It may be useful for other situations.

0:00 Video Timeline

0:03 The Plumbing Problem

0:50 Snappy Trap Fail

2:03 Solution That Works Using Rigid PVC

7:00 Final Install

The products shown here were purchased by me with the intent to use them. I did not receive any free items, and I am not being paid or compensated for this review. The video and description may contain affiliate links. If you click on a link, I may receive a commission. Money earned helps to support my channel and bring you more informative videos about engineering, crafting, and DIY.


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