Having lived for over 4 years and have always boiled and filtered our water. Many of my friends drink straight from the tap and they have been ok, but that's your own choice.
During the floods, I have seen warnings that have told everyone to boil water etc.
To be safe, only drink water if you know its filtered etc. Brushing your teeth from the tap won't do any damage.
If you're staying in a hotel, ask them first. Most of the water served in Hotels is OK. Other than that, I'm sorry I can't be much help.
In a restaurant, ask them it's filtered.