I am installing a utility sink in my basement and need to rework the drain pipe and standpipe for my washing machine in the process.

Original drain pipe and standpipe

Above is the original drain pipe and stand pipe that the washing machine used to drain into. I had to move the washing machine several feet to the right so I removed the copper drain and standpipe to be replaced with pvc.

removed drain and standpipe

This is the new PVC drain pipe. The original copper pipe was 1 1/4" and the new PVC is 1 1/2". I will be putting the utility sink in the empty space between the dryer and the white wall in the picture (the washing machine is immediately to the right of the dryer).

Should I try to implement something pictured below (but from left to right instead of right to left like in the picture) with the much shorter PVC drain pipe I have to work with (20" tall)? Is there a simpler alternative (washing machine to spigot trap under utility sink)?

enter image description here

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    It used to be common to just hook the washing machine discharge pipe over the edge of the utility sink and leave it at that... – keshlam Mar 23 '16 at 5:45
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    While you're at it, you should get rid of that fire hazard dryer vent tube, and install proper smooth walled ridged metal duct. – Tester101 Mar 23 '16 at 7:33
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    Dryer vent is getting switched out once this project is done. The inspectors I used when I bought the house missed that, some asbestos around pipes and other issues.... – Chris Mar 23 '16 at 13:26

Yes, the picture you included shows a good plumbing layout for a washer and laundry sink. In particular, it provides good ventilation for both the washer standpipe and laundry sink, and accommodates a P-trap in both locations (only the washer trap is shown because the sink trap will be installed outside the wall). Another advantage of this layout is that it uses a 2" PVC line for the washer drain, which is code for washers because a more powerful washer drain can overwhelm a 1 1/2" pipe.

You are working under some tighter constraints but it looks like you should be able to implement a similar layout. You might want to draw it out and see if you can achieve workable slopes (min 1/4" per foot) and get the vent pipe to the right height (above the overflow height of the sink). It may be helpful to swap the washer and dryer locations -- you should also switch the flexible dryer vent out in favor of some rigid ductwork.

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  • Thanks Shimon, this all sounds good! The only reason I might not switch the position of the washer and dryer is due to that gas line that leads into the dryer. I imagine I can switch it out easy enough, is there a problem with switching it for a longer one? – Chris Mar 23 '16 at 13:26
  • Actually, one more question. Is there any reason that the vent piping is 1 1/2" instead of 2"? Seems easier to just make it all 2". – Chris Mar 23 '16 at 16:01
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    I'm not sure on the limit for a gas line to the dryer. On the vent piping, it is simply done with 1.5" because that's adequate, allowed by code, and cheaper. Given that you're probably not a plumber with many different fittings and pipe sizes on hand, it might well be simpler to keep it all the same size – Shimon Rura Mar 23 '16 at 18:07

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