All flours can benefit from using the proper water, and it's no different for caputo. Your tap water could be fine, but if you want to play it safe brita filtered tap water is even better. At home I use spring water and it works great. I wouldn't use distilled water, since it is nice to have some minerals in there. If you really wanted to get freaky you could have a "goodie bag" made to add to distilled water that mimics the mineral content and ph of what is used in Naples.