My second floor laundry room has a pan under the washer connected to a 3/4" pvc pipe that terminates in the basement just below the subfloor of the 1st floor. I am finishing the basement and want to know the best way to handle this "emergency" drain. If I tie it into the sewer I will need a trap and maybe a trap primer. I have a floating slab and a fench drain in the basement. Can I extend the pipe to empty into the gap between my slab and the foundation wall and let the french drain handle it?

Hi Tfmc...

Seeing how a 3/4" pipe is really pretty darn useless in these cases I'd recommend placing the pipe into the french drain system and let any spill over fall into the drain.

That being said, I'd be more aggressive in protecting my second floor. You may want to consider installing a FLOODSAFE washing machine automatic shutoff valve... see image. There are numerous types available on the market but they all pretty much act as sensors that will sense a leak and automatically shut the flow of water to the washing machine.

This will not prevent overflow from a broken drain or an overflow situation, but then again, either will that 3/4" pipe...simply too small to do much in case of a real issue. What the auto. shutoff will do is guarantee that no additional water enters the washing machine and that is key..especially when your drain pan only has a 3/4" pipe. The auto. Shutoff is also great in cases where the hoses burst or start to leak.

Let me know if you want to discuss this more... OK?

Mark

PS: Please post any reply to the box at the very bottom of the page. Thanks.

In addition to Mark's excellent advice...

I would suggest you lead this drain to the outside. Wrap end with fine mesh to prevent bugs entering the pipe. Terminate it with 90 ell pointing towards the ground.