I didn't say that there wasn't one (now or then), only that I couldn't find one, and that an employee told me there wasn't one—and both those facts are true.
Also... "Responding to Prof Colbourne's comments, a spokesman for airport operator BAA said drinking fountains offering free water were already installed at Heathrow, Gatwick, Stansted and Southampton airports."
This is from 2002... http://www.dailymail.co.uk/health/article-355500/Free-water-...
http://www.heathrowairport.com/static/Heathrow/Downloads/PDF...
Gatwick: "once you're through security, you can use our water fountains or any of our food outlets will be happy to provide you with a glass of tap water."
http://www.gatwickairport.com/at-the-airport/flying-out/secu...
I also dont recall drinking fountains in Phnom Penh or Saigon's airports.
So I'm not sure what you are talking about. Maybe some of the smaller regional ones?
One potential hack around this is to find the disabled bathroom, which usually has taps with adjustable water temperature,
Ireland is not in the Schengen area