The milk bottles use a different plastic than the 2 liter soda bottles. I wouldn't use them, personally. Milk jugs aren't UV stable.
City water out of the tap around here has chlorine in it, so I don't bother. I've never had a problem with it, and I've gone weeks at a time on stored water.
Bleach I use for potable water I process from local non-potable sources.
On the grasping hand... use whatever you have to keep you and your family alive.
/johnny
The milk bottles are not the usual gallon jugs that milk comes it. The milk was Promised Land a high end brand, I would not have saved them if they had been the other kind. I don't know what UV stable means but on the labels it says they are recyclable.