It's really a little annoying to fill and empty the containers, probably the biggest negative to the appliance for me. If you run a steam or combi program, you have to fill the water container once, then again after the program is finished to rinse the oven. That also means two times emptying the drain water.

@malba2366: What did you decide to do? I'm having the same debate for exactly the same reason!

When I was looking at which combi to install I gave a bit of a favour to plumbed model knowing that steaming function would be used a lot. For full steam the water tank should cover 90 minutes per the manual for 1.4 litre refill.

Although refilling fresh water tray does not take much time, nor does emptying the waste tray, plumbing makes the usage very convenient. Wastage is drained out and this helps clearing out some smells such as fishy smell from steaming fish.

So, if the cost of pluming is not too bad, I would suggest a plumb version. The extra cost of plumbed version for the appliance itself is not a lot.

Do you stay awake at night concerned with all your existing water and drain lines in your walls/roof/under the house that all have the potential to leak and cause real damage?

The bigger risk for a leak is carrying the water and waste tray to and from the oven to the sink.

After using a non-plumbed combi-steam for a few months, I can see where the plumbed version would be desirable. It's especially a pain having to refill and empty the containers for the rinse cycle.

@Tim Sutherland, carrying the water is my concern too. So much so that instead of putting a steam oven in my appliance wall, I'm planning on putting it under-counter next to my sink. I've decided that I value not having to carry water over being able to easily see the controls (and get a sexy color -- you can't get the new obsidian in the plumbed model).

Carrying the water is really not a big deal, it's a fairly small container

@barbja99, it is unfortunate that you can't get 6805 in Obsidian black in the US. Our obsidian black 6805 is working hard on a wall. As dbabrams said, carrying water is not really a concern for a 1.4 litre capacity container, three steps for me to the sink. Even for a plumbed model, users still have to refill the container and empty it out manually in descaling program. Also every now and then empty the reservoir container, when wiping the whole unit dry. Miele recommends emptying the reservoir after each use or daily though.

doesn't the plumbed model have a drain? Seems silly to not be plumbed in in both directions.

Yes, 6805 has a drain line. Miele non plumb (6800 for example) has two containers, waste/condensate container and fresh container. For 6805, there is only fresh water reservoir. Plumbing takes care of filling the reservoir automatically, as well as draining out all the waste.

In descaling program, descaling tablets must be dissolved in the reservoir manually. Half way through the program, small amount of left over solution must be emptied out manually before the machine refill the reservoir with fresh water and rinse itself.

Emptying the reservoir after each use is mainly for limescale prevention per manual. I have soft water so don't follow Miele's instruction of emptying to after every use.