Just Googled it... UK£ 3800 to buy, and then whatever it costs to install... all in, probably not at lot of change from £10,000 in London - not including the penguin. Better spent elsewhere I think - just ask them to fill your bottle from the tap, if you like the taste of their water.
The irony is, they had a water fountain in the zoo for many, many years which was removed as part of the "improvements" to the lion complex so the fact they have now spent a reasonably large amount of money installing a new one is quite telling........
