I'm no chemist but a few things sound strange to me. Page 7 3rd paragraph he states that mains water "contains some good things that help stop corrosion"... like what? Further down the page he then states how mains water "may have excessive solids, hardness, clorides or sulfates" and then goes on to say how local water may add other chemicals that are not recommended for cooling systems.
Now as I understood people buy distilled water precisly because they don't contain all these chemicals and yet in paragraph 2 page 7 he states that "distilled water is the most corrosive". To me seems to be a contradiction there.
I googled this about distilled water:
Natural water usually contains a number of microscopic contaminants, along with dissolved minerals such as calcium and iron. One way to remove these elements from water is to boil it until it changes to steam, a process known as distillation. When this steam is allowed to cool down and condense into liquid form again, the result is a purified form called distilled water. Distilled water should ideally be nothing but hydrogen and oxygen molecules, with a PH level of 7 and no additional gases, minerals or contaminants.
Also from Wikipedia I found this:
Distilled water is also commonly used to top off lead acid batteries used in cars and trucks. The presence of other ions commonly found in tap water will cause a drastic reduction in an automobile's battery lifespan.
Distilled water is preferable to tap water for use in automotive cooling systems. The minerals and ions typically found in tap water can be corrosive to internal engine components, and can cause a more rapid depletion of the anti-corrosion additives found in most antifreeze formulations.[3]
Distilled water is also preferable to tap water for use in model steam engine boilers and model engines of other types. Mineral build-up resulting from the use of tap water in model boilers can severely reduce the efficiency of the boilers if run for long periods. This build-up is known as boiler scale.
Finally I personally believe Distilled water is best for our radiators as it's a poor electrolytic and electrolosis causes corrosion yes.
Found this on Answers.com :
Why distilled water is a non electrolyte and tap water is weak electrolyte?
because water itself, in its pure form H2O does not conduct electricity. what actually conducts electricity in water are the ions of other materials, which are present in tap water - various water treatment chemicals, metals, salts and minerals...
so since distilled water does not contain, or contains very few, of these other molecules, it is not considered an electrolyte.
So for me useing distilled water is the way to go.
Cannot comment about the anti-freeze but I had been told that too strong a solution of anti-freeze was bad.