Water is required for human explorers of Mars and it is also widely expected to be used to synthesize methane rocket fuel for the return trip (by combining the water with CO2 and energy to create methane and oxygen). Water could also be pumped into the lining or roof of a habitation to provide radiation shielding.
But how do you mine subsurface water that is frozen solid without heavy equipment?
The only think I can think of would be a drill with a head that emits heat or microwaves to melt the water and then it can be pumped to the surface and purified and processed. I'm not sure how practical that is. Would it make the ground unstable? Would you have to move the drill head frequently as each drill site gets exhausted?