Given enough available fuel for a fire and some fist sized rocks, I’d build a modified solar still. By digging the hole deeper and setting the collecting container up on a stand, you could put rocks heated in a fire under the stand and pour the contaminated water onto the hot rocks. I think that would be a lot more efficient than trying to rig a PSK tin as a distillery and since the fire doesn’t have any contact with the still, no worries about melting equipment.