This SODIS indicator goes from red to yellow in 6h
This is the final report on our project to develop an indicator for Solar Water Disinfection (SODIS). The goal of this project was to develp and test a low-cost device which can tell users of the SODIS method when the PET bottles which are used for this process have been exposed to sufficient amounts of sunlight. During the course of the project, we tried several approaches to solve this problem:
- Materials-based approach: Some materials change colour according to the amount of sunlight they receive. This fact can be use to produce a SODIS indicator, and in fact we identified a producer of an adequate product and carried out field tests with it. It works well in the field, but the drawbacks are the fact that the indicators can only be used once and that the price per unit is fairly high - 0.40$ may sound like a small amount, but each user family will need at least 10 to start with, and that's already 4$ - and then they will need more... However, the product works and the SODIS Foundation will continue to use it where it sees a need and a benefit in doing so - for example in situations where there is not enough time to train people thoroughly, like it is the case in some emergency siutations we are attending at the moment in Bolivia.
- Electronic approach. We have supported and collaborated with several groups (both research and private sector) around the world who are working on the development of an electronic device which measures the amount of sunshine received and tells a user when the water in the bottles is ready for drinking. Two of these groups went ahead to set up formal organizations (www.helioz.org and www.potavida.org, who we mentioned earlier) and are currently undergoing field tests of advanced versions of their prototypes. The advantage of these devices, as compared to a single-use device, is that they can be used for a long time (several years), which makes for an ideal training and teaching device. The drawback is the prize - but this will come down as the numbers of units produced increase. We will keep in contact with these organizations and actually may field-tests some of their products later this year.
Thus, we think that we have reached a stage where we can close this project. Over the past years, we have developed and tested several prototypes, supported research around the world and helped to establish two companies. We hope that this initiative will continue evolving and wish all the people and organizations involved all the best - for that in the near future, a SODIS indicator will be available for everyone who needs one - potentially, that would be at least 870 million people who currently do not have access to safe drinking water!
If you have questions or comments about our project, please do not hesitate to contact us (email@example.com).
At this point, we also want to thank all of the people who supported this project. Without these inputs, we could not have done all of this, and we also want to extend the thanks of all the people who directly benefited from this project.
Best regareds from the whole project team,