I use water deionised in a Milli-Q system for all my chemicals. The tap water here is hard, contains a lot of iron and is very variable between winter and summer, and between dry and wet years.
if you have any problems or doubts about your water, you should use distilled or deionised water for any ascorbate developers and for the final rinse, the former to ensure the developer is not deactivated by oxidation of the ascorbate, the latter to ensure you don't get drying marks.
Marty
Marty