Q Shoe Guy is just demonstrating his refinment and acclimatisation to the local culture.

There are hundreds of references to Japanese Tea Masters devoted to the water from a particular region or from a particular well in order to bring the most out of their favoured blend of tea for their ceremonies. The water in Tokyo will affect the taste of tea considerably and leave a faint scum on the surface (just as the water in London does - the scum is partly caused by calcium in the water interacting with the tea's polyphenols, you notice it most with black tea).

Ochanomizu (meaning: water for tea) is so named because the water for the Shogun's tea was taken from a river in this area.

Which water is chosen for any particular tea is a an age old subject that still inspires passions and controversy. Some tea houses have survived the centuries because of the water well in their grounds (I've been to one constructed directly over a well). Water that is still sought after by Tea Masters.

Don't think that only those obsessed with wines and other alcoholic beverages have the sole monopoly on being toe-curlingly anal about their choice of drink. You too can become a pompous tea-snob, haughty enough to rival any wine-bore. (Just don't go around saying that the water in Tokyo tastes perfectly fine... people will know you're bluffing!)