飲水機英文點講?

Normally we call it a "water dispenser" in Hong Kong.

You may wish to take a look at the following Watsons' website to see how they describe their products:
http://www.watsons-water.com/eng/co/index_wp.html

drinking fountain

water fountain
noun.
飲水器

Potable water machine

Drinking fountains

唔知你講緊邊種呢

一般黎講，我會叫water coolers

但係如果你要指明係果d礦泉水機／蒸餾水機，你可以叫Bottled water coolers

如果你係指果d按掣就有水噴上黎果d，你就可以叫 Drinking water fountains 或者就咁 drinking fountains

飲水機的英文係 drinking fountain~

Distilled water machine.