Both Zartemis and plllog here own Gaggenau steam ovens (I think the plumbed version), and there have been discussions here about plumbed vs. not. You might search those names, below (or via Google), for the threads.

There are food smells and then there are horrible gunk smells. If you leave standing water, you can grow all kinds of nasty gunk. Gaggenau has a drying mode. Mine is plumbed, and I don't use the drying mode, and haven't had a problem, but it's there. I certainly would dump and dry the reservoir in unplumbed if it were going to be sitting for awhile, and do a quick wipe of the floor and other surfaces, including the recess that the reservoir goes into. Why leave pools of water in a warm, air/moisture tight environment? Doesn't that sound like a recipe for pond scum?

I have gotten more info (once I looked up pricing for copper pipes I got desperate and called Miele in Germany). The water will be discharged at 70 Celsius, (which is 158 F)- can this go into a plastic drain pipe? If yes, which one exactly: ABS or PVC? The more detailed manual I finally gotten today states: Water hose data Stainless steel inlet hose length 1,500 mm (1.5m) (diameter sign: "crossed over O" 12.5 mm ) Connection to stopcock / connection to appliance each 33.5 mm (~ 1.5 inch) Plastic drain hose: length 3,000 mm (3.0 m) diameter: 12.5 mm (a bit short of 1/2 inch) Connection to odour trap / connection to appliance 15 mm (0.6 inches) When laying the water pipes in ducting, we recommend a minimum inner ducting diameter of 50 mm (2 inches). Connecting the drainage hose: Connect the drain hose to the odour trap using the hose connector (diameter 21 mm). Secure the hose using a hose clip. Am I reading this correctly that I need a 2 inch plastic drain pipe to connect to a waste hose of the appliance? US code stipulates indirect drain for steam oven, which I can accomplish, but 24 ft of copper? Do I really need copper?

I don't know of any one with glass, but the container in mine ( a Viking) doesn't really get warm - it is pretty isolated from the cooking chamber, and the water goes into a pump, then a boiler, before it goes into the oven. At the end of the cooking cycle, it does put some heated water back in the container, but not much.