My research thus far has acquainted me with a kind of trade-off: one can try to minimize the amount of contamination (from bacteria/parasites) or one can try to minimize the amount of particulates that could clog the filter. I concede there are many factors to consider, but it essentially boils down to this:

faster moving water has less contamination risk from bacteria/viruses as it's constantly being diluted, however faster water tends kick up more sand/silt particulates which over time can pose a legitimate clog hazard to the filter.

Other things to consider would be depth and temperature. If we go too deep we would encounter contamination from bacteria living on the nutrient rich bottom, but if we go too high, the higher temperatures enable bacteria/parasites to grow. Here is a cool picture illustrating this:

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Is there any way to have the best of both worlds; such that we both minimize the risk of contamination and clogging? I would imagine we'd have to put more effort in to it, so an assessment of whether or not it's worth the effort might be informative too.


2 Answers 2


If the water is muddy or there are swimmers, then the usual solution is to prefilter before treating.

A handkerchief is usually sufficient for filtering out all of the visible swimming bugs and sand/dirt although it won't filter out any of the things that will make you sick. Then you can treat/filter to kill the giardia/bacteria.

Of course, the precautions necessary depend on the area you are in and how severe the risks are.


In moving water put it in a bucket and let it settle for 12 hours.

In still water the top layer is solar disinfected. Solar disinfection

  • Not even going to ask.
    – paparazzo
    Sep 27, 2018 at 19:57
  • I once killed a filter in one morning - rain the previous night caused the stream to rise and get filled with very fine silt that a handkerchief would not trap. The filter did trap it, and clogged almost immediately. So, yes, I know have a one gallon collapsible 'bucket' so I can let the fine silt settle out before sending through the filter. Probably not a 12 hour thing, and I wouldn't count on solar disinfecting. And, the container can be used for the final boiling water rinse of dishes during cleaning.
    – Jon Custer
    Sep 27, 2018 at 20:32
  • @JonCuster Not suggesting you count on solar disinfecting - still filter. Just counter the assertion from OP that the top layer is bad.
    – paparazzo
    Sep 27, 2018 at 20:53
  • Understood! More commenting that I don't count on anything but the filter - one of the reasons I don't trust the UV water disinfection gear - how do you know it actually worked...
    – Jon Custer
    Sep 27, 2018 at 20:55

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