Water's boiling point is also a function of pressure. At 15psi, water won't boil until 250F. Hot spots can probably be beyond that, but even modest amounts of coolant will help reduce the issue substantially.
The only time pure water is going to corrode aluminum is if there's galvanic activity. This can be fixed by making sure the electrical system is properly grounded and only distilled (deionized is better) water is used. This is why tap water is a big no-no. It will corrode steel too, but often will attack other metals first. Use pure water, and the 'will corrode aluminum' argument becomes bunk. Which also negates point #2.
Using premixed coolant avoids the whole distilled/deionized issue altogether. Using a hydrometer and adding distilled/deionized to keep the specific gravity in check is good maintenance too. No one does that these days.
This 'Evans' stuff is an answer to a question asked only by those who don't maintain their cooling system and want a 'silver bullet' that's 'foolproof' to use. The right materials and normal cooling parts and coolants work exceedingly well, even in high performance situations. Sprint cars, pro stock, NASCAR, they all run water with a small additive package and do just fine to keep the engine cool. OEM coolants run for 50, 60, 100k miles before needing service. So why do we need to eliminate water? Why eliminate the typical glycol AF?
The mistakes most folks make are bodge jobs to to the electrical system, and adding water from the garden hose. Bad maintenance and piss poor work has over the years caused all kinds of grief that has spawned the snake-oil alternatives market for automobiles.
I'm sure Evans works just fine, but it's also likely no better than, and in most cases worse than a properly maintained 50/50 glycol package with a modest anti-corrosion package. Don't use your cooling system as a circuit, ground the engine block properly, use pure water or premix coolants, and you're likely to never have problems.
