Pete
That works in the good old USA, but overseas, even in airports for me, the risk is too great - especially right before boarding on a 12 hour flight with 1 toilet per 100 passengers. Too many times on my travels have I had to refrain from "I told you so" to companions who insisted that the local water was fine according to the guidebooks or authorities. One of the four movies we watched on the plane (yes 4 full movies and still plenty of time for food and the FREE wine on foreign airlines) was Sex and the City which had a hilarious but scatological scene based on one innocent slip/sip in the shower of a 5 star elegant Mexican resort.