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Update on Permaculture Pygmies – Introducing Solar Ovens, Water Filter and SODIS

We built a solar oven made out of cardboard, and showed the pygmies how to purify water through a solar disinfection unit (the SODIS System). We also showed them how to make a filter with a bucket full of sand, gravel and active carbon.

by Xavier Fux

Who said last days weren’t productive? Before leaving, we wanted to provide the pygmies with some very useful tools that can greatly simplify things for them:

  • Simple, easy-to-build solar ovens (to reduce the need for firewood and all the negative implications that come with it)
  • Sand-gravel-charcoal water filter (to clean the water from the 20,000L pond in order to use it for washing and other uses)
  • Solar disinfection system for water (to purify water from the 1000L tank)

We started off with the solar ovens, showing them how to build two different, simple models using only cardboard, aluminum, black spray paint, a piece of plastic or glass and adhesive tape. They helped us assemble both models and we provided enough materials for them to make about 10 more solar ovens. We explained that all they need is 30 minutes of strong sunlight.

They were thrilled at how simple it was and at the idea of cooking without firewood! Firewood requires walking long distances to collect and carry home, and is extremely uncomfortable to cook with because of the constant smoke, which is harmful to the eyes and lungs. They asked a lot of questions and even considered building some more long-lasting solar ovens out of wood.

We then demonstrated how to assemble and use a sand-gravel-charcoal filter, so they can eliminate silt from the water they collect in the new pond and use it for washing or anything else they need. The filter consists of two buckets placed one on top of the other. The top one has holes punched in the bottom, and inside are layers of sand, gravel and charcoal, covered with a layer of cloth. Water is slowly poured into the filter (goes through the cloth and the layers) and is collected in the lower bucket, almost fully transparent and free of silt.

Finally, we showed a simple method of purifying water using a plastic bottle and black paint (the Solar Disinfection System or SODIS). This is an effective water treatment method that consists simply in filling clean plastic bottles with water, exposing them to the sun for at least 6 hours, during which the water reaches a temperature of about 65°C (enough to kill most pathogenic contamination), resulting in water that is safe to drink.

SODIS is recommended by the World Health Organization and has been implemented successfully in many underdeveloped countries. The process is shown below:

After the three final demonstrations, it was time to say goodbye…. We once again explained the importance of maintaining everything that was put in place and continuing the work in cycles in order to have constant food production for the village. We stressed the importance of watering the raised beds, keeping the pond clean, keeping the 1000L tank closed and gutters free of leaves, taking care of the nursery and replanting seeds two weeks before harvesting the mature vegetables, etc.

We thanked them all for allowing us to work with them and for working so well with us. We encouraged them to continue, with Jeph’s help, keeping the two fields packed with food into the future, and applying what they learned to plant on all the other open spaces they have on site. We told them we were impressed by how fast they learned the new techniques and reminded them how lucky they are to live on such fertile land. There are so many places in the world where people struggle to produce food in the most difficult climates and conditions, but living in Congo, all they need is to learn to love their work, and they can achieve long-lasting abundance!

Chizungu thanked us and welcomed us to return one day, so they can greet us with vegetables from their own produce!


  1. The term pygmy has for me some negative connotations. It appears to me to be ethnic group generalisation based on height (i.e. they are short than us). To some there may even be an idea that being smaller means somehow undeveloped. Anyway, it would be good to name the peoples (e.g. Aka, Efé, Mbuti).

    It’s great that healthy solutions are being spread.

  2. Thanks for your comment Stepehen, There is truth to what you are saying. Eventhough in most of the world these peoples are refered to generally as Pygmies without any negative connotation, in some contexts, the term has been used to mean “people that are less than 1.50m in height”. I also agree that it would be better to call them Batwa which is the way that they call themselves.

  3. Great things you’re doing. Thank you…. Do you have an article or page with complete details on how to build the oven and filter? I’d like to teach this to the homeless living in their cars and tent cities in the United States. Local fire departments often keep them from using camp fires and gas generators. Also, this might be a dumb question – for SODIS, do the bottles have to be plastic or can glass jugs be used? I hate to use or recommend plastics of any kind if I don’t have to, especially if they get warm or hot.

  4. Dear Michele, Thank you for your kind words.
    You can find detailed plans in various languages to make various types of ovens both from cardboard and wood in the following link:
    As far as the SODI system, yes, glass bottles can be used as long as you also paint half the bottle or jug black. Hope the following link can be of help to you.
    I wish you all the best in your project with the homeless

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