Engineering students from University of Washington  have  Create Inexpensive Water Testing Tool  to monitor water disinfection using Solar Power / Sun rays. They have won an international contest for their design and got $40,000 prize from the Rockefeller Foundation and are now working with nonprofits to turn their concept into a reality.

Using the sun’s rays  is a primary way to disinfect water or minimize the water-borne infections. But one problem with many systems is the user doesn’t know when the water is finally safe to drink. That’s where the students at University of Washington step in.

Team member Jacqueline Linnes, she and other students treated their drinking water by leaving it in plastic bottles in the sun when recently after completing her bioengineering doctorate, traveled to Bolivia last year with the UW chapter of Engineers Without Borders.

University of Washington reports that they used parts from a keychain that blinks in response to light, they made a device which is similar to one that is used in a solar powered calculator which monitors how much light is passing through a water-filled bottle and how many particulates are obstructing the light. When enough particulates are removed, the sensor indicates that the water is now safe to drink.

The UW entered a competition to design an indicator for Fundación SODIS, a Bolivia-based nonprofit dedicated to testing and promoting this method. Solar disinfection in water bottles removes more than 99.9 percent of bacteria and viruses, with results similar to chlorination.

The students estimated that the solution could be retailed at just $3.40,  making it a viable solution for many non-profits that provide this kind of support to communities.