Just like beer, bad water makes bad tea and coffee. The local muni water supply is so bad I have to use purchased water for beer. I'd do the same for coffee but I drink too much coffee to spend the money on a water supply for my coffee. I do use a faucet mounted filter for my coffee water supply as well as my regular drinking water. It isn't ideal but it strips out most of the foul aroma and flavor in the water. At least enough that I can enjoy the coffee.