Laundry discharge pipe size?

[werlax]

We're in the process of planning a remodel of our basement and would like to move the laundry upstairs for the time being. It will eventually move into a new space that we'll create, but that'll be "as the budget allows" and might be a year down the road. The closest water/drain location is the bathroom. It would merely be an issue of tapping into those lines (which are about 5 feet away). I'm concerned that the flow of water would be too much for the sink drain. Currently, the water drains into a utility sink and down into a crock that has a pump. The pump pushes it out into the septic tank. The sink drain would go to the same location. Thanks for any help!

[Speedy Jim]

You are wise to be concerned. The washer drain needs to be 2" pipe.

More importantly, it can NOT simply discharge into an existing sink drain. To do so will very likely cause siphoning of the trap serving the sink.

Ideally, the 2" washer drain (with its own trap) would tie into the main stack. Even there, one has to be careful to vent the washer trap correctly to avoid siphoning issues.

Not to rain on your parade, is there any temporary hookup possible, like a drain down to the existing sump?

Jim