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    http://www.motherearthnews.com/diy/home/how-to-make-a-solar-still-ze0z1209zsch.aspx

    How to Make a Solar Still

    DIY Tutorial
    by Jason Wiskerchen

    Monday, October 26, 2015, 7:12 PM

Learn to make your own distilled water and other liquids using these DIY solar still plans. A great weekend project to build resiliency and have more water security.

http://www.motherearthnews.com/diy/home/how-to-make-a-solar-still-ze0z1209zsch.aspx

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2 Comments

  • Fri, Oct 30, 2015 - 4:25pm

    #1

    robohobo

    Status Member (Offline)

    Joined: May 20 2015

    Posts: 1

    Be careful with chemically-contaminated water!

    One MAJOR issue not mentioned in the article: solar stills (and other distillation processes) work because water evaporates at a lower temperature than contaminants, which get concentrated in the "still bottoms" left behind.  This is great for many types of contamination, but cannot be considered safe – by itself! – if the water in question may be contaminated with chemicals that evaporate/boil at a lower temperature than water.  This includes many toxic organic petrochemicals (VOCs) that can contaminate water after a disaster, spill or underground tank leakage… think benzene, MTBE, TCE, and many other common groundwater contaminants.

    An example of this is the concentration of moonshine alcohol in a still – in that case, the alcohol boils lower than the water, so the 'contaminant' (water) is left behind while the alcohol is condensed and "purified".  Another example is the use of "air stripper" towers to remove toxic VOCs from groundwater at superfund sites – the volatile contaminants evaporate away much more easily than water, lowering their concentration before the water is used. 

    Perhaps before sealing up a still one should leave the water exposed to the sun for a little while – ideally while being aerated – will help remove VOCs by promoting their evaporation before the distillation process starts, at the cost of some water loss due to evaporation.  A charcoal or resin filter may also be appropriate as a secondary filtration step after using a solar still if the water might be contaminated.  At least it couldn't hurt!

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  • Fri, Oct 30, 2015 - 9:15pm

    #2

    dgbd

    Status Member (Offline)

    Joined: Jul 21 2014

    Posts: 2

    Plans for Solar water distillation

    Hello Robohobo, 

    After making multiple solar ovens I find this simple design compelling for distilling water.  I collect rainwater and I am looking for ways to purify that water for drinking in the future that minimizes energy inputs.  (I use it for garden watering at this point).  I think I would work to make it more responsive to a wider seasonal use than around the summer solstice by increasing the angle of the glass to about 40 degrees from the horizontal. Water seeks it own level so just tipping it up won't work like it would with a solar oven.  I think where I live at about latitude 45 that would extend it's usefulness from about the spring equinox until the first week in October. I would also improve on the "pex" gutter set up. It would be interesting to see what form it would take.

    dgbd

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