Water quality is a major contributor to an enjoyable cup of tea.
The water should be clear and free of any sediment and minerals. It also should be freshly drawn because the oxygen content of fresh and running water is high and contributes to the enhancement of tea quality.
Unfortunately a lot of tap water has minerals and additives so filtered water (never distilled) is best.
The kettle for boiling the water should be emptied after use as stale or reheated water will diminish the quality of the pleasing cup.