[david-given]

Tap water in the UK is heavily chlorinated. If you go to a country which doesn't chlorinate tap water it's like night and day.

(I live in Zurich. The water company here say that comparing Zurich tap water with bottled mineral water is unfair --- their tap water is considerably better.)

[anexprogrammer]

Not sure if it's down to how hard the water is in each area, but here (NW England), a fairly soft water area, you never notice the chlorination. You notice the chlorine quite a bit in London, along with the free limestone in every glass.

[amouat]

Tap water in the UK varies greatly around the country. The water in Edinburgh seems pretty good, some other parts of the country taste surprisingly different.