For making up formula:
If you're in Melbourne, tap water boiled for 5 mins would be fine. In HK, either get a good filter and boil... or use distilled water and boil.
We also cook our baby's food with distilled water. My partner is just wrapping up a job here replacing fresh water pipes in Kowloon and he said we are absolutely not to use tap water for drinking without boiling. It's just easier to use bottled, and it's pretty cheap here as well.