Babys milk made with filtered water?

[Beanmistriss]

Hiya people. My sister has come to stay with her baby. He is 11 months old nearly. It say on the back of his milk tub that you should not use artificially softened water to make his milk with. Theres loads of limescale here so we use filter jugs to filter the water before boiling it. Would that be ok to make his milk with or should we use it straight from the tap and then boiled? Theres no limescale where they live so we've never really had to think about it. I have posted this in family but thought I may get a quicker answer here. Thanks