They say everything is made of atoms?
Sand is made mostly of silicon dioxide whereas water is dihydrogen monoxide. As such, changing sand atoms to water atoms would require changing silicon to hydrogen. This would involve some sort of nuclear fission that would both be grossly inefficient, energy hungry (the energy generated by the fissioning of atoms would not be enough to equal the energy that would have to be put in to make the fission) and beyond the capabilities of humans for quite some time to come. Even if it could be done, the energy required to do this would be much more than transporting the things around.
