Fish Filter - Water Purificatiom ?

[Mortblanc]

If you need a cheap and efficient system the slow sand filter is the way to go. It can be made from materials at hand or kept for just this purpose; some gravel, some sand, a plastic bucket or trash bin and a few feet of PVC pipe.
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If properly built and maintained it will service a family indefinitely.

I have known some bumbling DWI attempts that did not work but that was due to not following the instructions for construction or maintenance, which as simple enough if your IQ is above your shoe size.

Slow sand filters were the first method used by metro utility departments to purify water for major cities, so they have over 100 years of time proven utility. This system is what erased cholera epidemics from modern society. I believe it was the first system London used to supply safe drinking water.