All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The Fatwa that we adopt here in Islamweb is that it is permissible to boil Zam-Zam water and use it in cooking or for other uses (purposes). However, we are not aware of any legal evidence which prohibits this. On the contrary, it is confirmed in the Sunnah that it is permissible to drink it, and we do not see any difference between drinking it directly or drinking it after boiling it or drinking it with something else.
Rather, what should not be done with Zam-Zam water is to disrespect it and use it for filthy purposes, like for removing an impurity and the like.
As regards drinking it and cooking with it, then this is permissible because it is food that nourishes and a cure for diseases.
Allaah Knows best.