Mom and daughter in Haiti can use the sun to purify their water

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Solvatten (meaning “sun water”), the hinged 11 liter magic black box designed by Swedish inventor Petra Wadström, is a deluxe Solar Water Disinfecting device.  SODIS is a free, amazingly simple treatment  to remove pathogens from untreated water, requiring only plastic PET bottles and sunlight.  After 2 to 6 hours in the sun, ultraviolet rays have rendered the bottles’ contents safe to drink. It is recommended by the the World Health Organization, UNICEF, and the Red Cross. 

There are two obstacles to main SODIS adoption.  The first is, simply, lack of awareness.  NGO’s have done a lot of education and promotion (EAWAG has taken the lead), but marketing an  unbranded, free technique is hard.  The second hurdle is lack of end user confidence: how can something so simple actually work? (There are a number of SODIS indicators available which address this problem.) For larger quantities of water, filling and emptying bottles is unwieldy, since an optimal SODIS container is 2 liters.

Chemicals leaching from plastic bottles into their contents during the SODIS process have been shown not to endanger human health.  

SODIS is a cost free, zero carbon-emitting treatment, since it consumes no energy.  This produces significant savings and improved air quality for families who now boil their water oover wood-burning stoves. A surprising fact:  heating water to 149°F kills all disease-causing organisms (bacteria, viruses, and parasites). Boiling to 212° provides visual confidence that the water is safely treated, but the energy consumed to raise the temperature over 149° is unnecessary. It takes 2 pounds of wood to bring one liter of water to a boil, so imagine how much timber is collected and consumed, unnecessarily. The wood is generally collected by girls and women, yielding is a large time dividend when that burden is lifted.

Petra Wadström demonstrates her  invention, the Solvatten

Enter Petra Wadström, a Swedish microbiologist and artist, who lived with her family in  Indonesia and observed  how much time and labor went into transporting and treating water. Determined there could be a design to accomplish this much more effectively, she began the eleven year process of creating the Solvatten.  It is indeed elegant on many levels, speeding up the SODIS process while doubling as a water heater.

It weighs about six pounds empty; with its two sides filled with water, around 31 lbs.  (The ubiquitous jerry can weighs in at 40+ lbs when filled).  The container opens to lie flat, maximizing exposure to UV rays.  The push-button indicator turns from red to green  – the international sign for Good to Go – when the internal temperature has reached pasteurization level.  In direct sunlight, this can be in under two hours, allowing for multiple pasteurization cycles each day.  Users are warned that the clean water is very hot – water heaters are generally set between 120° and 140°, and the Solvatten water is over 150°, all from free sunlight.

Solvatten is headed by Wadstrom and works with NGO’s; units are now being being distributed at around $35 via NGO humanitarian partners in Haiti, Kenya, Nepal and Uganda.  Solvatten has qualified for coveted Gold Standard Carbon Offset Credits, due to its preservation of forests by eliminating the need to use wood to boil water for purifying water.  Since end users save fuel expenses, there is also market demand to purchase them.  Solvattens are being distributed via microenterprises,  purchased by people for both business and domestic uses.  Here’s an inspiring example, to warm an environmentalist’s heart:

Washing dishes at Matsula’s Kawempe, Uganda Restaurant

Matsula’s restaurant. First we meet Mastula, she runs a small restaurant and she markets her business in a clever way. For every meal she serves, she also serve a cup of safe water from Solvatten. Her customers trust her when she explains about Solvatten, so she doesn’t serve water in plastic bottles any more. This has increased business within a few months from 50 meals to 70-100 meals per day.

Two Ugandan women sell Solvatten-ed water pouches to local kiosks. Using two units, on a sunny day they can package up to 180; if it is cloudier, they still clear 120, earning up to $5 a day.  At that rate, a Solvatten pays for itself in a sunny week.  An owner of a hair salon uses the hot water for shampoos, lowering her expenses considerably.  Yes, give women better tools, and watch their creative innovations!