S.O.D.I.S. Water Purification

From the slums of Nairobi to the most remote corners of the Andes, clean water is a necessity. But without significant investment in sanitization infrastructure, this resource is incredibly difficult to provide. But after years of research and development, a cheap, reusable and nearly universally effective system of water treatment has been developed.



It’s called SODIS which stands for Solar Water Decontamination, and requires only a source of fresh water, a clear plastic bottle and sunlight. It sounds impossible, but the science behind it is solid. Sunlight contains a great deal of ultraviolet radiation, which disrupts the genetic processes of bacteria reproduction and can destroy the microorganisms cell walls. Ultraviolet radiation also has an ionizing effect on the water itself, creating highly oxidative compounds like hydrogen peroxide, a common household antiseptic. While it may be difficult to believe, all it takes is six hours sunlight to destroy the microbial inhabitants of a bottle of water, rendering it fit for human consumption.

As you can see, not only is this water purification process useful to the peoples of third world countries but, it is also beneficial to the wilderness traveler and survivalist.


8 Responses to “S.O.D.I.S. Water Purification”

  • Andy:

    Hi – SODIS has been around for a while, but hasn’t caught on (in developing countries) because there are a number of significant use/social disadvantages. Probably the two most important are that very few people like the taste of (warm) water that has been kept in a hot plastic bottle for a few days; and that, in practice, the amount of (drinking/cooking) water that a family requires (usually a minimum of 10-20 litres per day, assuming a five-member household) requires the rotation of an enormous number of plastic bottles: 10-20 litres on the roof/in sunlight; 10-20 litres being cooled; 10-20 litres being used/refilled … and the unfortunate reality is that most families can’t be bothered to keep up this routine when the end result is warm, de-oxygenated and unpleasant tasting water!

    Sorry, it sounds a great idea and has been pushed by the Swiss and Swedish development agencies for any number of years … with little recognition that it has not caught on because of these fundamental shortcomings. Perhaps more viable out in the bush, but only if the water is relatively clear to start with (as it is not effective in killing pathogens hidden in clumps of suspended solids, e.g. silty water).

    Cheers – andy (independent water and sanitation specialist with 23 years experience working in developing countries in Africa and Asia)

  • Tony:

    Hi Andy,

    Thanks for your comment. I completely agree with what you say. The logistics of using the SODIS method to supply all the water requirements of a houselhold would be time consuming.

    However, as you mentioned. This method is well worth being aware of regarding water procurement in the bush. Water would have to be filtered to remove debri etc. but, once this is done the SODIS method (although not perfect) is better than nothing in a survival situation.

    I have only suffered from serious dehydration once and that was enough for me.

  • Nicodemus:

    Will this work with Platypus Bottles?

  • Tony:

    Hi Nicodemus,

    To be honest, I really don’t know if Platypus bottles would work. I’m afraid I have never used or even seen a Platypus bottle, other than one being advertised on the internet.

    Having said that, as long as they are clear and not opaque I can see no reason why they shouldn’t work.

  • Thank you very very much, in the end, after long days and even weeks of searching, I found something unusual. Yours!!

  • Filter the water first. Otherwise bacteria and viruses will hide from the UV radiation in the shadow of particles of debris.

  • Wow! Thank you! I always desired to write in my site
    something like that. Can I take part of your post to my
    blog? Wonderful Job, Chow!

  • Tony:

    Hi Jessie,

    Feel free to use anything you want. As far as I’m concerned, information should be shared. Not hidden away.

Leave a Reply