I'm trying to make a drain decision before drywalling my laundry room walls. I currently have a standard top-loading washing machine, draining into the laundry tub sink, which drains into a 1-1/2" pipe (which connects to a 2" drain pipe below the concrete floor), but am planning to buy a front-loader eventually, and place it on a pedestal.

A wall mounted plumbing box is in place, where the supply valves live, but a stand pipe isn't roughed in yet.

In pondering my drain options, I'm considering these options:

1. Drain the new front load washer (from its pedestal height) into the laundry tub. Since the manufacturer recommends that drain hose be 29" above bottom of washer, the washer would drain into the tub at about 12-18" below the recommended level. Not sure how big a deal this is, honestly.

2. Install a 1-1/2" stand pipe. This would be relatively easy to do (by a plumber), and would be at the recommended height, but would the washer overwhelm it? Some say they have no problem with 1.5 inch, others say that only a 2-inch drain will work adequately. (yes, I know that 2" is required now).

3. Dig up the concrete floor, so a plumber can install a 2-inch stand pipe, and connect it to the 2-inch pipe under the concrete. May be the best option, but also more expensive.

So those are the choices I'm considering. Looking the the best option and lowest cost, but don't want to make the wrong choice. If there are better options, I'm all ears!

Thanks!

Go with #3.
The new washing machines will overwhelm a 1 1/2" pipe. Here in NC we have to use 3" pipe on the horizontal run.

I'd either install the larger standpipe, or I'd continue to use the laundry sink. The sink will work fine with any washer you drain into it and is the lower cost option for you, unless you want to get rid of the laundry sink for some reason. It is best if the washing machine discharge hose empties into the standpipe or sink from a height that is the same or higher than the top of the washing machine water level at its fullest, that avoids having a siphon problem.

Also, using the laundry sink lets you easily add a lint trap/filter to the end of the washer discharge hose to catch all the fibers that would otherwise go down your drain and can cause problems. Many people get clogs somewhere in their drain pipes due to washing machine debris going into the drain. With your setup you can avoid that potential problem. The washing machine lint traps come in a variety of styles, you can even use a knee-high hose stocking. And they make filters that mount on the wall so you can have the washer drain hose at the proper height recommended by the manufacturer.









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I would go with option #3, if 2" is code required at your locale. I'm on my second front loader in about 10 years, on an 1½" drain/trap/standpipe and have never had an overflow.

Option #4



Speed Queen

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Thanks everyone for the replies. I'm no longer sure that the drain line under the concrete is 2" (floor drain nearby is only 1.5" so I'll be using the laundry tub for the washer drain.

If I raise the new washer on a pedestal, I'll have to concoct a home-made air-gap to get the drain high enough... Not sure how I'm going to make that not look like a hack though!



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The wall-mounted filter and air-gap device pictured above or something similar can be mounted to the wall just above your washing machine, even if it is on a pedestal. Then use whatever length of drain hose is needed from the filter and air-gap device down to the laundry sink. Isn't that all that is needed? And the benefit of having a filter plus the air-gap is that the filter will keep all those clothing fibers out of your drain pipe, they do cause a problem in some homes.



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