Never had a problem from using black water or grey water tank. Took extra care tho. It was no hassle for me to carry jugs of water from my home for drinking and cooking. I used the fresh water tank water for showers and other uses.
I refilled my jugs at the campground. An RVer once told me he caught someone trying to drop cigarette butts in his fresh water intake. I have heard others seen folks pouring something into another RVer's fresh water tank. Different strokes for different folks. Never been sick while camping for many years only bug bites. Just saying.
