What do you think about me preparing tea using half drank bottles of water.
Are you sure you want to drink so much half drank water?
I think it's fine.
I think that's a bit nasty. I think using the best water you can find would be the best option.
I mix the half drank bottles with other water and I have a new tea.
While that's a good way to use up your bottled water, you should probably just stick with using fresh water. Tea tastes at its best with the freshest of water that you can possibly find, maybe feed your plants with your old bottled water instead?