Why is Billion Bottle Project excited about solar disinfection?
Well, we know know how devastating a lack of clean water is throughout the developing world. We know that in addition to harming the health of individuals, lack of clean water is also stifling education and economic opportunities. Furthermore, we know how immediately impactful a cheap, easy to use sanitation method could be to these communities.
To us, SODIS is that method.
SODIS uses a combination of heat and UV-A rays to kill disease-causing organisms and disinfect water (2). You store water in clear plastic bottles and place those bottles outside in an area accessible to sunlight, such as a roof, for 6 hours in sunny conditions or 2 days in cloudy conditions (2). After that continuous exposure and the work of heat and UV rays, the water will be disinfected of germs and thus safe to drink (2).
However, SODIS is a mixture of pros and cons.
- Confirmed to reduce germs in water
- Shown to reduce diarrheal disease incidence, the leading killer with unsafe water
- Easy to use by individuals
- Minimal cost to use (can recycle plastic bottles)
- Little change in taste of water
- Less chance of recontamination since water is stored and disinfected in bottles
- Material, color, and shape of bottle must be considered
- Reduced effectiveness if the water has higher turbidity (more cloudy, hazy, unclear)
- Different regional climates may not align with length of required sunlight exposure
- Limiting in how much water is disinfected at a time
- Individuals must know how to properly use SODIS method to know when water is safe to drink
And while organizations like WHO, UNICEF, and the Red Cross have promoted SODIS as a useful method of water sanitation in developing countries, its adoption remains inconsistent (3).
That’s where BBP comes in.
We’re looking to make SODIS easier to use for its users. We are doing this in a few simple ways, starting with OSPRI (4). OSPRI is a dye based sensor we are developing. It is placed in the SODIS bottle and changes color once the water has received enough sunlight, signaling to users that it’s safe to drink (4). This takes the guessing out of SODIS. With OSPRI the user will not have to worry about different bottle materials, water cloudiness, and weather conditions that may affect the SODIS technique, but it maintains the cheap and easy to use hallmarks of SODIS.
It is our hope that a device like OSPRI will help make SODIS easier to adopt globally, furthering our goal of universal access to clean water.