Microwaving water does nothing to the molecular structure or composition of water - it will add heat (energy) to the bonds within the molecule, but it won't make it into anything else besides H2O.
Saying it damages it on the molecular level is a load of crap. While it is true that microwaves can damage things like proteins and DNA (due to conformational changes, breakdown of COMPLEX molecular structures, etc), it will NOT cause a molecular change in H2O. Last time I microwaved water it didn't turn into anything else, if I recall correctly.
Documented on the internet? Lots of stuff is documented on the internet - unless it's peer reviewed by experts in the field, it's only as good as the next site about ninjas swallowing frisbees when they get really ****ed.
Maybe the water needs to be cooled first?
