What type of sink do you have? If it's one of those deep laundry sinks made of fiberglass/plastic or concrete, you can simply hook the drain hose over the side of the sink. Those sinks are large and deep enough to contain the drained water until it can pass through the drain. If your sink is a small lavatory type or one built into a countertop, the sink may not be deep enough to contain the volume of water pumped by a washer. Even a front-loader. Washer drain pumps move a lot of water very fast.

You can't just tap into the sink drain line. Not only would it be in violation of the plumbing code, but you very likely would overwhelm the drain line. Sink drain lines aren't big enough to handle the sudden surges from a washer drain pump, which is much more powerful than a dishwasher drain pump. Washer standpipes are usually required to be a minimum of 2" in diameter, and extend to a certain height above the trap.

I was looking at the manual for the washer (Bosch Nexxt and they have a picture of one hooked up to a dishwasher tailpiece. I am doing new construction, so I will spec a 2" drain line. I think that any overflow would back up into the sink temporarily. (This will be a built in install with a cabinet and sink similar to a kitchen.

Chris

Be sure to check your local plumbing codes. In Europe, drain connections similar to a dishwasher tailpiece are fairly common and legal. While I'm not a plumber, I don't think that type of connection would pass muster in many places over here.

I know that in my laundry room, I had to have a separate standpipe for the washer, even though there's a sink just like you're planning, right next to it. My Miele laundry pair is under a countertop, so the standpipe doesn't show, because it's behind the washer, under the counter. The shutoff valves for the washer water supply bibbs (which are also below the counter) are built into the wall above the counter (they look like shower valves).

Thanks for the info James. Your approach seems like the best solution.

Chris

There might also be the issue of the height of the standpipe. The appliance installation instructions should tell you, but sometimes if the stand pipe is too low the water will drain out of the washer tub when the tub is full. Normally if the rubber drain pipe forms a loop about 6" higher than the washer water level, it will be okay.