Water Purification for the Third World

Access to clean water is a well known problem in developing countries. UNICEF estimates that 4,500 children die ever day as a result of unsanitary water and that one in six people lack access to clean water. The staggering statistics go on and on.

The Watercone Solar Still

The Watercone Solar Still

Water Distillers USA Solar Still

Water Distillers USA Solar Still

Though some water distillation and filtration systems exist, such at the Watercone and Water Distillers USA Clear Choice Vapor Still, they are expensive (from $50-$200) and hard to distribute to the third world.

One thing that is ubiquitous in many developing nations is trash.  What if there was a way to use trash to purify water?

That was the goal that Brooke and I had in mind when starting our final project for Future Craft.

There are many types of water contaminates and each can be taken care of using different methods.  Below is a chart that Brooke put together to help explain:





Pathogens such as E. Coli

UV Radiation, Chorine, BioFilm-Settling Filtration, distillation


Arsenic, fertilizers

Varies (ex. Ferric Hydroxide)


High turbidity, colored, debris

Settling, coagulation or flocculation (AlSO4), simple sand filtration, distillation

We decided to try to use a 2-liter soda bottle to clean water three ways: filtering, distilling, and UV radiating.

Luckily, by being clear, the soda bottle is already great for using UV radiation to help purify the water.

After much experimenting, we were able to take find a way to make a single cut about 2/3 the way up from the top of the bottle to quickly and easily turn a typical 2-liter into a filter system and a distiller.

For the fulilter, you takethe top part you cut off and use it as a funnel, stuff it with cotten (or cloth is fine), then cover that with small particles, like rice or sand.  Top it off with medium sized particles, like grabel or pebbles, and voila – you have a filter! You can place the funnel on top of the cut bottom of the 2-liter to catch the filtered water.


Here’s the complete filter:


Here is a video of the filter in action (sorry, it’s sideways….).

Solar Still

Now that the water is filtered and at the bottom of the 2-liter bottle, remove the filter and instead place the distiller in the top of the bottle.  The distiller is made by folding the cut top part of a second bottle in and up to produce a ringed trough around the inside of the top part of the bottle.

Place the distiller in the sun and let the water from the bottom evaporate, condense on the sloped walls of the top bottle section and run down into the trough.  When the trough is full, gently pick up the top part of the bottle, unscrew the cap and top slowly to pour out the filtered, stilled and UV-radiated water!

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2 Responses to “Water Purification for the Third World”
  1. Janet Covington says:

    Your filtration explanation is clear, but your youtube doesn’t show the part I can’t figure out – how to cut the bottle to do distillation.

    • Heather says:

      Hi Janet,

      Thanks for pointing that out what I had overlooked – that I didn’t have any pictures or a clear explanation of the distiller!

      I don’t have great pictures of how we did this, but this instructable does a pretty good job.

      Basically, cut the bottle as you would for the filter, but instead of filling the top part with rice and sand, instead, fold the cut edge of the top part up, inside the bottle to create an internal trough to catch water. In the instructable, they placed this bent top piece on a black towel. In our example, we places it over the cut bottom part of the 2-liter bottle that held the filtered water.

      Thanks again for the input and please let me know if you have any more questions!

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