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My tenants recently told me that they have constant clogging problems with their bathroom sink and had me come take a look at it. I found the following 3-trap configuration:

Three traps??

This was done because the sink is too far to the right for it to mate with the drain in the wall via a standard p-trap configuration. This seems like the wrong solution to me (it was done by a (non-plumber) contractor when I was living out of state). A guy in the plumbing section at Home Depot didn't like it either and suspected that it would lead to clogs.

I replaced two of the traps with one of those flexible pipes and was able to make the connection with the remaining trap being rotated slightly - not ideal, but I'd suppose that two (roughly) 45˚ bends are better than what was there previously. There seemed to be no alternative way to connect the sink to the drain given the 1-1/4" pipes and fittings available at HD.

My Questions:

  1. Is it fair to say what was there before was incorrect and was contributing to the frequent clogging problem?

  2. What is the "right" way to solve this plumbing problem?

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Awesome! I've never seen a W trap before. –  Tester101 Mar 28 at 10:02
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3 Answers 3

up vote 4 down vote accepted

Much too much up and down! You want a P trap with an additional angled connector toward the wall.

The first down and up from the sink drain is correct. That is the P trap. It should end with a horizontal leg pointing toward the wall (an L shaped piece).

ptrap

This will not line up with the opening in the wall because the drain is offset. Therefor that leg will run a distance and then will use an angle to bend it back toward the wall.

You could use a right angled slip joint connector (running horizontally).

slip elbow 90

A 45 degree angle would be better (the less sharp the bend, the less likely to stop up). However it may be hard to fine a 45 degree slip joint elbow. You could use standard pipes and elbows, but these would require glued joints rather than slip joints.

Finally there should be a straight run from the angled connector to the wall connection.

You can rotate the P part of the trap so the L leg coming off the P is parallel to the wall (assuming you are using the 90 degree elbow; if not, adjust accordingly). Then the elbow turns the drain toward the wall. Another horizontal run carries the drain back to the wall.

You need to measure the length of the horizontal leg of the P and the length of the connecting run to the wall; be sure to allow for the sections embedded in the elbow and trim each accordingly. Assemble.

It is easier done than described.

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Ah - I was thinking something like this 90 degree elbow had to exist. They didn't have any in 1-1/4" at the Home Depot I was at. Will find one somewhere and fix this the right way (eliminating the flexible pipe I used) next time I'm on the property. Thx! –  Ryan Dlugosz Jan 30 '13 at 2:46
    
@thatRD Found this listed on the HD site, but may not be in stock at all locations. Other box stores or plumbing suppliers may have. –  bib Jan 30 '13 at 2:50
    
You do need a 90, but (at least around here), you need a "long sweep", which has a much larger radius bend that the fitting pictures. The key is that you are changing direction from a horizontal pipe to another horizontal pipe. Such a transition needs a long sweep. The short sweeps (as pictured) are used when changing from horizontal to vertical. As noted in the answer, it might be hard to find the proper fitting with a slip joint, and you might need to use PVC pipe that is welded together (with primer and then solvent). Make sure that the new pipe is sloped so that water will properly drain. –  Pigrew May 23 '13 at 17:31
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LOL, yes that is incorrect! The two trap version (S trap) used to be legal, but no more. The "snake trap"(??) was never legal. It is certainly more prone to clogging, but I'll wager there are other contributing factors.

Correct fix. Keep the first trap out of the sink and the last arm going to the wall. Discard the other two traps. Remove the trap arm adapter at the wall. Install a flat 45 degree ell on the pipe in the wall such that the ell outlet is pointing to the sink trap. Add a short length of pipe to the ell, then a trap arm adapter. Reinstall the trap arm to the adapter and connect the downward facing part to the single trap. Check for leaks.

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You need to start from the tapped fitting using a 2" 45' fitting if it's a sink, or a 11/2" 45' fitting if it's a vanity, then trap arm, then P-trap (depends on size), then a tubular extension, then a tail piece. You are done!

If you have multiple sinks in the kitchen only, with outlet drains separated no more than 30", place the one trap in the center then take tubular elbows from the outlets to a tubular tee then to the trap. Multiple sinks to a single trap is not valid for vanity or bathroom sinks.

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