[cjrp]

To be clear, it's not my recommendation but the NHS' - https://www.nhs.uk/conditions/baby/weaning-and-feeding/drink...

The filters are things like this https://www.tommeetippee.com/en-gb/product/perfect-prep-repl...

[krisoft]

I read the linked NHS document multiple times and I can't see any reference to filtered water. They only talk about boiling the water. Where are you seeing that they recommend filtering?