re using water, as an emergency I sort of understand, but as someone mentioned, you really dont want to use water as freezing issues will damage seals etc.
I once had a motorcycle used racing, and requirements were that anti-freeze/water mix was not allowed on track, as a leak would be very slippery and wouldnt evaporate, so those of us with water cooled bikes removed it and replaced with water.
Forget it and store the bike in an unheated garage, and voila, damaged head gasket. I was lucky and got away with only that , no cracked parts.