Technologies to avoid the spread of infections in water

What can we do to avoid getting infected when traveling to countries with poor water reserves? In these areas diarrheal disease, mostly caused by water and food contamination, is the second leading cause of death for children under 5 years old and results in the deaths of over 750,000 children every year. It is largely preventable.

Janice Boughton, MD, has been doing some research on the available solutions to avoid getting sick during her trip to third world countries, or areas affected by natural disasters. In her summary she mentions the importance of hand washing and hand sanitizing at several points during a day before, along with the fact that water purification is the most vital and yet unattainable procedure around these areas. Janice gathered some effective, low cost technologies to make drinking water from almost any source of water. To avoid water related disease, we must kill or remove parasites, their eggs, bacteria and viruses.

  • Water boiling – if water is boiled for a minute, virtually all microorganisms are killed and it will be safe to drink;
  • Chlorine – toxic to just about every living thing and a little less than a teaspoon of bleach added to 5 gallons (~19 l) of water and left to sit for 30 minutes (the chlorine molecules must reach all of the intended targets) will be safe to drink. The EPA quotes 8 drops of bleach to sanitize 1 gallon (~4 l) of water. If it is left awhile the chlorine gradually evaporates and the taste improves. One must remember that bleach does lose potency over time, and that these proportions apply to fresh bleach, 5-6% sodium hypochlorite. Although chlorine dioxide is more expensive, leaves no chlorine taste after evaporation;
  • Povidone iodine – the 10% solution that is used as a medical skin prep, is effective at a concentration of 1:1,000, which means 1 mL (15 drops) in a liter of water, when left for 15 minutes. It also doesn’t taste too bad, but will turn purple if mixed with starch, so is quite alarming if used to cook pasta. Tincture of iodine and iodine tablets are more potent but a little harder to come by;
  • UV-C light – harmful to microorganisms, UV-C light attacks DNA and RNA, the genetic materials of cells, and kills everything whose function depends on these. Recently small pocket lamps have become commercially available which can be used on the fly. It is an excellent way to treat water from the tap or water that has been filtered or is visibly without particles;
  • Sunlight – it is also possible to purify water by placing it in a PET plastic container in full sunlight on a roof for 6 hours, using both the heat and the UV to kill anything living in it.

“Ceramic filters, like those used for backpacking, remove all but the smallest viruses. Unfortunately hepatitis A and E, which cause lots of bad disease in developing countries, are not removed by ceramic filters and can be present and infectious in water. These filters are very compact and can be used to remove bacteria and protozoa from huge quantities of stream water, as well as removing undesirables like pine needles and algae and grit. They are absolutely fine for most uses but are not adequate, alone, for places where virus contamination is an issue.”

A few years ago a British engineer came up with a super fine filter that eliminates viruses as well and is very simple to use. The name of the company is Lifesaver and it has been marketed to the military and well as being introduced into water limited settings where people drink from puddles with obvious contamination. They use low pressure pumps in a bottle or jug to push the water into a reservoir from which it can be used.


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