I've got lots of work like this, and have had people come out and say all your stuffs going on my windows, and i've explained to them that all it is is (pure water) it won't damage your window,
and they've been ok about it, but i got a plan that if some one did take it further, i would suggest just cleaning one or two of their windows now and again for nothing just to keep em happy,(not all) because y it wouldn't be fair on the ones that pay, all the one's that have come out too complain so far their windows were f***king mank,
just tying it on.