I read in the book "Baby Love" by Robin Barker that it was fine to use boiled water from a jug for making up baby's bottles. Just empty out any water already in the jug, and fill up with fresh water before boiling. Before that I used to boil water on the stove for 5 mins, so the jug has certainly been easier! I never had any problems , although my baby was about 6 weeks before I changed over to doing this. I think the younger they are, the more careful tou have to be.