The tapwater in my town is very good to drink, but it is very hard. So when I have a new tea, I brew it with tapwater and with bottled water determining whether it is worth to spend some money on bottle water on this tea.
The bottled water I use is one of the less mineral on the market in France. Only 19mg/l total dissolved solid. You can see its composition: here
I use it with quite all Japanese and Chinese greens. For Puer and Oolongs too if I brew them in my zisha and duanni teapots. So I chose bottled water in the poll.
This morning, nonfiltred tapwater Keemun Mao Feng with my breakfast