Yacobito,
I don't know if this helps you, but I used "ultra pure" water for about 10 years in FW tanks. My dad worked for a purified water company for 30 years, so not only did I get the benefit of a lifelong education in water (I emaphasise the LONG), I also has access to all the water I could want from the plant. I filled up my tanks with it, I did all my water changes with it, and never had any problems because of it.
The systems they used were the most advanced (and costly) in the bottled water business. For that reason, the company eventually could not compete, and was purchased. The system was: a UV sterilizer, charcoal, 3 stage RO (the third stage is the TFC membrane), and DI. If forget the actual numbers, but it calssified as AR (analytical reagent) grade water. In fact, the machines were equipped to add minerals back to it for drinking,
There are a couple things you can do with this pure of a water (like what you are talking about) to demonstrate what pure water can do. You said your boss only drinks coffee using that water. If you look inside the coffee machine there will be no mineral deposits. Because the water has almost nothing in it, it actually acts as a solvent.
IMO, if you can get it, use it. BUT, since there is nothing of value for your critters in it, you are going to have to make sure you put in the appropriate nutrients/minerals etc. You have to do that anyway, but this way, you know you are starting from zero.