I want to avoid a 90 degree bend under slab. However, I have to reduce from the 2" pipe that drains the WM to the 3" main drain line, and the reducing tee I find has a very small sweep. Do I need to use a reducing combination wye and is there such thing?

If I dig out a small section of the basement to connect a 2" WM drain to an existing 3" drain pipe coming from an upstairs toilet, can I leave the underground pipe at 3", as it is, or do I need to upgrade to 4" which would require me to dig out across the entire basement to the main waste line to the street?

Thanks for help

Hey Pompopei:

Leave the underground at 3"...just be sure to connect 2" washer drain to the 3" using a 3"x2" wye fitting..ok??

When you come out of the ground with the 2" drain use a 2" long sweep 90 (see pic.) and add a 2" dandy clean out (also called a test tee) just after coming out of floor (see pic.).

The washing machine drain itself needs 2" ptrap, 2" standpipe out of ptrap between 24"-30" and an 1.5" vent that connects into other vent in the house.

Here is a picture of what drain should look like (or at least similar)... (where the TY fitting is that picks up sink on right... you should install the dandy clean out there)... ignore the sink drain and vent on right of picture!!

And that standpipe coming out of ptrap into the washing machine box needs to be increased a bit (24" to 30").

Let me know if need more... Mark

You need to use a 3" x 2" WYE fitting (see pic.) or a combination wye 1/8 th fitting (sorry, no pic... but resembles a very longgggg sweep TY fitting......NO tee fittings of any kind allowed underground.

See your other post...I answered more of your question there.