There is absolutely no need. the antifreeze is there to increase what is known as colligative properties. it increases the range of water phases (ie solid, liquid, gas) from pure water at 0 - 100 oC for complete sublimation to something wider (e.g. -10 - 110). Ie the temperature absorption or performance doesn't change just the amount of energy required to change the phase from liquid to gas, or liquid to solid. Added to this is an anticorrosive compound.
You don't require any of these properties as the operational requirements of your WC loop wont go below or above the liquid phase of pure water. Plus there is nothing to worry about with corrosion if you use proper kit.
The only thing you can do with coolant is cause problems, don't do it because its all risk, and no gain.