We sanitize our fresh water tank with bleach and water, then with baking soda and water to make it smell better. That said, we bring bottled water and bottles of water from our tap at home for drinking and brushing teeth. Just personal preference and my neurotic tendencies.
If we are on a site with full hook ups (aka, FHU), I attach a filter to the white hose before it attaches to our rig. We, too, have a regulator (ours is metal and bends at a 90 degree angle so it's asy to attach to the input). We don't camp with FHU very often at all, so typically have a third to half a tank full of fresh water on board. Happy camping!
