question! can I use tap water to mix in with my baby's formula ?

No

yes you can. just boil it , then cool it .

would NOT recommend it unless you take care to purify it

Definitely Not a Good Idea. They Have The Nursery Water at Any Food Store or Bottled Water Works Good Too

We've always use tap water. It's perfectly fine.

There is nothing wrong with using tap water.

I always use tap water and my kids are fine

you CAN but its not recommended. If you do then boil the water then store the water in the fridge

you can but boil it. distilled water is best.