Saving the environment 
one WADI at a time

WADI is a solar powered UV measurement device that visualizes the process of solar water disinfection (SODIS) in PET or Glassbottles. It is placed alongside bottles that are filled with contaminated water and exposed to the sun. Once the process is completed, a smiley face on the WADI confirms that the water is safe to drink. WADI is endorsed by the WHO, meeting its microbiological performance criteria and is classified for providing targeted protection.

WADI is simple, reliable and easy-to-use. Obtaining safe drinking water with WADI can be achieved through five simple steps.

  1. Fill PET- or UV-permeable glass bottles with water
  2. Expose the bottles and WADI to the sun, and press the reset button
  3. You can track the progress bars for a few hours while the water is disinfected
  4. Watch a happy smiley face appear on the display when the process is completed
  5. Water is safe for consumption.

The smiley face appears as soon as the incident UV-dose reaches that of the reference values stored in WADI and the water is safe to drink (removal of 99,99% of common bacteria and other pathogens). WADI in combination with SODIS is highly effective against bacteria and pathogens.


Solar Water Disinfection (SODIS) describes a natural process, during which UV-radiation from the sun eliminates harmful pathogens and bacteria in water. PET plastic bottles are filled with water and then exposed to sunlight. Over time the sun’s UV-radiation will make the contaminated water safe to drink. The SODIS method was researched and developed by the Swiss water research institute Eawag and is approved by the WHO and UNICEF.