Do we know if the water in the toilets (anticipating smart answers, I mean from the taps) is of drinkable quality? If not I suppose one could bring a camping stove and kettle to boil it prior to consumption :)
Take your own bottle tops in to place on the bottle purchased. Joking apart £1.90 for a lukewarm bottle of H20, albeit it with bu**shi* printed on it explaining how wondrous the water within is :eek:
Water fountains and byo own lidless containers would probably generate far more in goodwill...