I work at a power plant, and we condense steam through a turbin too generate electricity. Last night at work we popped a hole in one of the lines and it got me thinking about this question. Remember guys, it was very late. Lol. Didn't consider the fact that the boiler is a closed system. I agree with most of your comments now that it has been discussed a little. And I've added more cons. When I'm in my shop, say painting a fish, there is a very fine overspray from the airbrush that would end up in that dehumidifier too. And not just skin particles from me, but I'm sure that thing is ingesting micro particles from the animals I'm working on too. I am not going to bother testing that water, I'll just keep using it for the plants only, and stick with ro/di for my tank. Thanks again.