Non conductive Fluids are worse performing!
Most Water Cooled systems use Distilled water along with anti corrosive and anti Bio additives.
You might think OMG WATER + Electricity = BAD!
Water that has suspended ions like Salt, Calcium, pretty much anything that comes out've your Tap is electricaly conductive.
In
http://www.xtremesystems.org/forums There have been some people who have a leak and have all their componets drunched in water with the system still running. They just calmly turned off the computer fix the leak, let it dried for a day or so and their systems were up and running again.
Let me say again Distilled water IS good, however make sure to clean up your Water blocks, Radiators, pump, tubing, hell everything with Distilled water and alcohol 90% or higher consintration.
No matter how many people say use Vinegar to clean... Dont listen... It makes Oxidies on all of your copper parts. Vinegar = acid = bad