Tap, bottled, and filtered waters are all different. Bottled water doesn't have to come from a mountain spring. It can be nothing more than city tap water in a fancy package. There are many types of filters - some are excellent and others useless. People often find tea tastes different elsewhere than it does at home.
Water is usually the culprit.
In the past, tea merchants blended their tea to accommodate the water of a particular city. We provide only true teas, no blends. The brew is in your hands. We encourage you to experiment with filtered water and bottled water to find those you like best. And remember for great tea, don't re-boil water as much of the oxygen will disappear, resulting in a flat brew.