Connect washing machine drain to stack with kitchen sink?

[Andrew Garvin]

I’ll do my best to describe the situation and question accurately:
The two bowls of a kitchen sink connect to a double sanitary tee on a 3” waste stack. The branches of the tee are 1- ½“. The only thing above the double tee is a 2” vent line. Below the sanitary tee is a cleanout tee. About 10" below the cleanout tee is a slab on grade.

If permissible, I would like to connect the drain line from a washing machine to this waste stack. There’s room between the slab and the double sanitary tee to shift the cleanout tee upward (closer to the sanitary tee) or downward (toward the slab).

Can a sanitary tee (or other connection) be inserted in this vertical assembly for the washing machine drain? If so, is it important whether it’s above or below the cleanout? If such a connection cannot be done, why not? I’ve been told third hand that code will not allow such a connection, but no explanation has been provided.
(The trap of the washing machine would probably have an independent vent, so that’s probably not an issue.)

 

[Terry]

The cleanout can be installed where it's accessible. You're fine with moving it.
The washer is a 2" p-trap and standpipe with a 1.5" vent.

 

[Sponsor]

 

[Andrew Garvin]

The cleanout can be installed where it's accessible. You're fine with moving it.
The washer is a 2" p-trap and standpipe with a 1.5" vent.

Note: I was slightly incorrect with my description of the current conditions... The double sanitary tee into which the double-bowl kitchen sink flows is 2" with 1½" branches/arms (not 3"x 1½" as originally stated); there's a 2" bushing in the top of the cleanout tee.

Terry --

Thanks for the incredibly quick reply, and on a holiday weekend to boot!

If I understand you correctly, as long as the cleanout remains accessible, it can be shifted [a] up closer to the sink's double sanitary tee, to make room for the washing machine connection below it, or down to make room for the washing machine connection between it and the double tee. In either case, I'd add a 3" x 2" sanitary tee for the 2" washing machine drain connection.

You didn't cite any code prohibition on draining the washing machine into the same stack as the kitchen sinks, nor on how close together vertically two sanitary tees can be, so -- pending further input from him -- I have to tentatively conclude that the contractor's reference to a plumber saying that code wouldn't allow the connection I propose (and that he'd have to run the new drain a longer, more difficult way, to a different waste stack) was mistaken. I'll give him the benefit of the doubt: neither he nor the plumber could see what was behind the back panel of the kitchen sink cabinet (I had to dismantle a lot of it to make it visible).

Thanks again!

-- Andrew