View Full Version : Draining a Washing Machine in the Basement

Ben Wilson
10-20-2009, 08:33 AM
Hey guys,

I just bought a 1950 house where the only ideal place to do laundry is in the basement. The previous owners had simply drained the washer directly into the floor drain (via an ABS standpipe strapped to the block wall), but I'm guessing that this is not a code-approved practice.

Assuming that using the floor drain is not OK, I figure the most economical solution will be to install a laundry tray that drains to an above-ground pump. I've never installed a pump before and I have a few questions:

1. The pump will lift about 7' and then drain over to the existing stack about 10' away. Do I still need to install a trap and vent at the top of the lift (i.e. do I treat the top of the lift as being like a normal fixture drain)?

2. The laundry tray will drain directly into the pump - do I need to install a trap and vent between the tray and the pump? I can't see why I would, given that there are no sewer gases that can rise out of the pump... but maybe I'm not considering something?

3. The existing stack is cast-iron, and I'd really like to avoid cutting into it. At the bottom of the stack is a Y-fitting with a cleanout. Can I simply extend the cleanout and install a Y to drain into it from above?


10-20-2009, 02:04 PM
Can you post a picture of the waste stack and the floor drain?


10-20-2009, 02:54 PM
I have something similar to option 3 at my house, but it's not vented and probably isn't code compliant. Yhere is a utility sink on that 2" drain too. The stack is next to the sink and the washer is next to that so it's not going far. No traps siphon.

Anything with pumps is going to be a PITA one day when it breaks. Not to mention that the washer has a pump that can drain very quickly so you might need a larger pump on the discharge, plus you don't want it to run dry....yada yada

Without seeing pictures, I would recommend extending the clean out so that you can tee off with a 2" (right, guys?) line and route that to the washer and place a trap and stand-pipe for the washer. If you can find a place to tie a vent in, that's great, otherwise you could use an AAV if it's code compliant in your area.

Ben Wilson
10-21-2009, 06:05 PM
Attached are a few pics to describe the situation. Note that the stack is about 4' from the closest wall, so draining directly to the stack without a pump is not feasible.

Here's the stack with the "standpipe" and floor drain in the background:

Here's the stack with the cleanout at the bottom:

Here's a closeup of the cleanout:

And here's the floor drain:

10-21-2009, 08:11 PM
Bust up concrete and tie into the floor drain? May not be code compliant, but it might be easiest...

Will a washing machine, with a long enough hose, pump overhead to the stack perhaps?