The problem with just running water is that you don't get any of the surfactant or corrosion protection that Water Wetter or Engine Ice offers. Plus, Water Wetter is accepted at most racing facilities.
I hate to get on my soap box about this, but I am afraid the weird internet rumor that it is best run straight tap water for coolant if you use alcohol as a fuel is just that, a weird internet rumor. I wouldn't be surprised if it started over on PS. :biggrin: