antifreeze info chemical Man
Is it OK to put water instead of coolant?
In general, using water as coolant is OK for a short time or as a "get you home" alternative, but it does not have the anti-freeze and corrosion inhibiting properties of a proper coolant mix, so should not be left in the engine for any length of time, especially if you live in a cold climate.
What temperature does water freeze in your car?