Try this site for more on conductivity of water.

I've tested freshly deionized water n a nuclear power plant (that's as pure as it gets...) as part of my job when I was in the in the US Navy. (been 12 years since I dealt with it... is why I forgot the second ion, but its covered at this site)

http://www.gvsu.edu/wri/education/ma...nductivity.htm