Question:
I would very much like to know what researchers think of thecurrently available labortory water purification systems.

Is there anything that needs improving?

Can stuff carry over into a still and would cleaner feed water intothe still be desireable? How many people use other technologyrather than stills? Why?

Answer: The last few labs I've been in have all used a cartridge systemto purify nominally ("house") deionised water. If theresulting resistance is >18 Mohm it is considered pure(unless we suspect contamination by organics). From brief teststhe water is also RNase and DNase free. On one occasion I found that it was impossible to performa particular assay (sensitive assay for reduced glutathione)using still-purified water as contaminants caused too muchspontaneous oxidation (EDTA could not cure it) whereas usingcartridge-purified water the assay ran beautifully. The only improvement I could think of would be in price(but that would improve just about any product