I have a 2nd floor laundry "closet" -- just the washer & dryer, both full size, in a closet with folding doors. When I remodeled, I had a floor drain installed in the floor, and had ceramic tile laid onto the floor, along with tile wainscoting. I wanted to ensure there would be no leaks from this closet. Everything works well, no rattling/shaking going on, and it's been in place for nearly 5 years. I'm delighted with the results. The tile closet opens onto hardwood floors. Both the hardwood floors and the tiled floors are laid on top of sub-flooring that's made of particle board, if I remember correctly.

Anyone? Bueller?

At first glance the floor drain idea sounds like a pretty good idea, but when you think about it, the only thing seperating the inside of your lovely home from a filthy sewer, is the U-bend water trap in the floor drain. No problem if you flush it regularly, but if you let it dry up you're going to be waking up to the lovely smell of sewer gas. However, this would work if it can be connected to another drain, and then have both drains flow into a U-bend trap. That way the other drain would presumably keep the U-bend closed off. I'm not a plumber though, so please treat this as speculation, not a suggestion. As far as putting the washer in a tub is concerned, I tend to agree with your sales person. The risk is that it will lower the friction between the washer and the floor, and your washer will start walking all over the place. It's true that a washer on a pedestal is going to weigh 250 lbs plus, but the problem is resonance between the washer and the floor, not that the washer isn't weighing enough, because these resonances are specifically caused by the washer being so heavy. So, if you have a vibration problem with the washer, it's specifically because the 250 lb weight of the washer is interacting with your flexible floor. Weedmeister's suggestion regarding manual single handle water valves actually has quite a bit of merit, because if you think about it, you realize that you're dealing with probabilities here. Let's say for aurguments sake that the odds of you having a broken water hose is 100,000:1, and the chance that you would forget to turn the hose off is 100:1, you can calculate the chances of you having a flood as 10,000,000:1, and you've effectively turned the remote possibility of a flood from a broken hose into something that's impossible for all practical purposes. The trick lies in being able to train everyone who uses the washer to turn the valve handle to the off position after every wash load.

Bubble-level doesn't have much relation to vibration. Reduction of vibration is primarily related to all four corners of the machine equally supporting the weight. However, a substandard floor structure can't be compensated by that. Whether the machine is absolutely 100% bubble-level and the weight equal on all four corners, any oscillation of the drum during spin will transmit into the floor.