My cousin and one sister in law does this all the time, they give you the water and more water if want, its your stuff your putting in . In the scheme of life I would not worry and go for it . My father in law while he does not add anything always always only drinks water and even asks for some lemon or lime for his water and never has has a problem. I see no problem, now if you perhaps asking for another refill of soda and pouring that into a plastic bottle and taking it out that is tacky. Good luck. Peace. Catherine