[6ppc]

The practicalities of moving huge masses of water into and between orbits are not to be trifled with.

Short term you are correct, but long term the same drive system could be attached to large chunck of ice in the outer system and boosted anywhere we need it. Short term see my earlier post about using ground based rail guns or lasers to boost to Earth orbit.

[6ppc]

chunck = chunks

[r9etb]

Nice thought, that stops short of the full solution. Example: rail guns cannot put anything into orbit.