Okay
[https://curiosity.com/topics/you-should-not-drink-ultra-pure-water-its-dangerous-curiosity/]
Just like, I would iamgine, a sip or two of Dawn wouldn’t send you to the floor in convulsions, a sip or two of pure water wouldn’t either. But you asked for reference to whether it is harmful to the human body? Yes, emphatically, it is.
Draw your own conclusions.
Yes.
This is exactly why pure water is so good for cleaning. It naturally needs to recolonise itself with minerals and does so by taking in all the stuff we want to clean off the glass. It is an unbeatable universal solvent. The more we coat glass with soap concentrates (we are now being encouraged to add neat concentrated soaps directly to the FliQ etc applicators) the more needs to be removed. That way, instead of leaving glass clean, we leave a thin soap residue which attracts more dirt. Good for repeat business/more frequent cleans but not good for our or the general environment.
WFP is the way to go for me at least. I spent over a decade the old way.
Tip: Cut back on the amount of soap and change your squeegee rubber! 
I often hear people say when I call “No, we don’t need it done yet, they still look great from the last clean.” Crap, how can that be, there is soap all over it! lol
