Mr. Rawles,
Regarding the filter design suggested by “Dim Tim”: Consider replacing the modified stockpot with a sink. A deep stainless utility sink would be ideal, would require little alteration, and could be set up outdoors at the downspout to drain directly to a retention barrel or bladder. In a SHTF scenario, an existing indoor sink could be modified by removing the trap underneath the sink. Collected water can then be poured into the sink, filter through, and drain underneath (a food grade plastic five gallon bucket fits quite nicely.) Regards, – Tamara S.