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Using the Sun to Make Water Safe to Drink

In 2001, Bob Dell left his career as a water treatment scientist to volunteer for children affected by AIDS in Africa.  But when he followed a group of Ugandan children to their local water source and saw that they drank from the same pond as the cows, he found a whole new focus for his expertise: finding a clean water source for these children.

Dell returned to Kisoro, Uganda with equipment to see how bad this “drinking” water really was.  What he discovered was shocking: the water the children shared with the local cattle contained 14,000 E. coli bacteria per 100 ml.  To put this into perspective, in the U.S. water systems are shut down if just one E. coli bacterium is found in 100 ml.

When Dell asked local parents if their children were in poor health, they responded as though he had asked about the weather:  “Oh sure, my kids get sick all the time from constant diarrhea.”  This problem had statistics to back it up:  Two million children die each year from waterborne diseases such as cholera and typhoid fever.

After some initial tests, Dell discovered that solutions such as water filters or wells were not sustainable because they required too much maintenance.  Dell says, “I saw so many abandoned water wells in Africa, I couldn’t believe it.”

waterschool3-internal.jpgThe solution came from a technology discovered by accident in the 1980s by Aftim Acra, a professor at the American University in Beirut.  Acra left a bottle of contaminated water on the windowsill of his lab one morning.  Upon retrieving it at the end of the day, he discovered that the germs in the water were gone.

Further tests showed that the water had been purified by the sun’s UV rays, which have the power to kill bacteria, viruses, and parasites  through a process now known as Solar Water Disinfection (SODIS).  Dell explains that putting water in a PET bottle (the kind most soda and water comes in) and leaving it outside for six hours will kill 99.999 percent of the bacteria in it.

Not only is this technology simple, but the countries that need it most–such as Haiti at the moment–all possess its key ingredient: direct sunlight.  SODIS can be used year-round between the latitudes of 35 degrees north and south, a band that encompasses nearly all the places where waterborne illnesses can be lethal, especially to children.

After piloting the SODIS technique in Kisoro and seeing the diarrhea rate there drop dramatically, Dell, along with Fraser Edwards, founded Water School.  This Canada-based non-profit teaches children in underdeveloped countries to use SODIS.   It also emphasizes safe hygiene practices such as hand-washing and depositing human waste in a safe place.

Dell says that children now come home from school and identify water their parents are drinking as the kind that used to make them sick.  They insist on using SODIS in their households, and Water School provides the first set of bottles for each family.

The impact of the Water School extends beyond physical health.  Because children are not getting sick any more, they can attend school more frequently.  School attendance rises 20, 30, or even 40 percent in communities the Water School has reached.

Dell knows that teaching children good hygiene means it will become a part of their culture in the future: “What’s really exciting is that after I’m gone, these kids’ kids are going to be OK too.”

Water School also ensures the endurance of its programs by putting the community in charge of them. All Water School branches are run by locals.  In Uganda, Water School employs 12 Ugandans full-time, and only Ugandans sit on the organization’s board of directors.

Explains Dell, “We’ve transferred the responsibility to them so that they don’t have to depend on us. That’s the beauty of it.”

Thanks to Water School, more than 400,000 people are now using the SODIS method to avoid getting dangerously ill.  The program has reduced diarrhea by 80 to 90 percent in many communities.  

Water School now operates in Haiti as well, and is working to help contain the cholera outbreak there, where more than 1,000 people have died after drinking water contaminated by flooding from Hurricane Tomas.

waterschool2-internal.jpgThe biggest remaining challenge for Water School is to convince people of the program’s potential. When Dell first introduced SODIS in Kisoro, one man, Peter Bahizi, went home to his family and laughingly told them that a voodoo man had arrived saying he could use the sun to make water safe to drink.

But Bahizi also said he had nothing to lose in trying SODIS, and after it ended his family’s constant illness he became one of Water School’s strongest advocates.

As for Westerners, Dell knows they will see the positive effects of the program when they see it in action.  A woman from Rotary international who visited a Water School told him, “‘I have never seen such an impact from a program in my life.  Everyone I talked to said their children aren’t sick anymore.'”

This is Water School’s goal, and it continues to take steps to achieve this.  The group will have charitable status in America by the end of the year.  Dell hopes that support from Americans will help the organization expand its reach in Haiti and other countries because, as he says, “No child in the world should die from drinking bad water.  I can’t accept that.”

Photos courtesy of the Water School.

© Food Safety News
  • Gretchen,
    Thanks so much for this wonderful article. I’ve forwarded it to our local Rotary Club, which has been involved in water projects in Africa.

  • Gretchen,
    Thanks so much for this wonderful article. I’ve forwarded it to our local Rotary Club, which has been involved in water projects in Africa.

  • Use glass bottles instead, or open containers, not plastic.
    Avoid using plastic as food containers. Water is an excellent solvent and causes all plastic to leach into solution.
    I stored water in two different types of clear plastic bottles (one that milk is normally sold in, the other one that fruit juices get sold in, all thoroughly washed) for perhaps 2 weeks, inside my cupboard, alongside with water stored in a plain clear glass bottle. I then examined the waters by taste and viscosity.
    The waters stored in plastic had a faint but clearly detactable off-taste, not of the milk or the juice they stored before, but an odd plasticky taste. The water from the glass bottle (which previously had fruit juice in it) tasted perfectly like water.
    Next I examined viscosity by pouring. Water from the glass bottle dribbled easily, just as my control did – which was water straight from the tap. Water from both plastic bottles did not dribble easily. When being poured it formed a continuous oozing string of water, no breaking in the string.
    The plastic did something to it. Whatever this may have been, its viscosity was altered.
    Viscosity or “stickiness” is basicly the strength with which molecules of a substance, such as water, hold together. The stronger the force with which molecules attract one another, the greater is that substance’s vicosity.
    I also successfully purify tap water of chlorine by letting it sit exposed to the sun for half a day (in Australia). No chlorine taste to it after that whatsoever.
    I could never achieve this effect by boiling it, not even for an hour! It always tasted of chlorine.

  • The SODIS process uses a PET plastic bottle because the plastic is thin enough to allow UV rays to penetrate it, and because this type of plastic has none of the harmful chemicals such as BPA that have been connected with plastic lately.
    Please visit Water School’s FAQ section at http://www.thewaterschool.org/faq.html for detailed answers to questions about why they use the bottles they do.
    Thanks so much for your interest!

  • The SODIS process uses a PET plastic bottle because the plastic is thin enough to allow UV rays to penetrate it, and because this type of plastic has none of the harmful chemicals such as BPA that have been connected with plastic lately.
    Please visit Water School’s FAQ section at http://www.thewaterschool.org/faq.html for detailed answers to questions about why they use the bottles they do.
    Thanks so much for your interest!

  • What a great article. ¬†At Sahbu we also believe that mothers who are educated, are more likely to ensure their children are safe, healthy, and that they also are educated. As these traits are passed down through generations, the cycle of poverty and violence is broken, and entire communities improve.