I imagine some fancy lab has managed to produce extremely pure water, probably from oxygen and hydrogen gas.
I often wondered myself if anyone had an application that needed them to do this. I suppose the hydrogen and oxygen can be made, as pure as possible, but how pure can they really be? Can we purify them better than we can purify water? Will they pick up contaminants, in the tubing on the way to the reaction vessel? And how do we make them react? With an electrical spark, but what two electrodes?
And what is the new, "pure" water held in? At least some contaminants can come from a glass vessel, even a fused quartz vessel will release some silica. Not to mention what you can get from borosilicate. And soda-lime glass is completely out of the question. So what's the container? Rigidly pure platinum-iridium, of the grade used for the kg standard? Will that leach nothing? I'm not sure.
What about dissolved gases? Trace pollutants, carbon dioxide, will dissolve in water. Can you make a good enough vaccum to remove all traces of them?
So ... perfectly pure hydrogen and oxygen, piped in platinum tubing, into a rigorously evacuated platinum chamber, with a platinum electrode to make the spark. All to do, what, exactly.
Which, of course, is a question for
The Captain: what is the application you're thinking of? What do you need the purest of the pure water for?