Where to find more information on SODIS
Asked on behalf of others:
A friend of mine operates a small NGO in Gambia and they have been asked about using solar disinfection as a water source for a rural community which they serve. He is not a WASH specialist (all the staff have regular jobs and run the charity in their spare time) and he is keen to get some further information.
Is SODIS something you have any familiarity with and if so do you know of any resources that he could access which might give him a bit more information on this? I was wondering if you know of any other websites which might be of use here and which might go into the practical details of implementing a SODIS scheme and the pro’s and cons??
The best resource on Sodis is probably http://www.sodis.ch/methode/anwendung/index_EN . As WaterAid we do not actively develop or support it, as our believe is that the water needs to be safe from the source and household treatment should then not be needed. SODIS has been particular promoted for peri-urban areas (bottles are easily available and metal roofs present). However, the proper use is quite tricky and as such it is often not regarded as reliable.
Any other experiences to share?
Hello, Arjen's resource is indeed the best. The Akvopedia page) also has some useful links.
A disadvantage not always mentioned (especially by proponents), but that I have heard from a couple of local NGOs in Kenya and Tanzania, is the possible growth of algae, which while not being health risk still make the water less attractive, and SODIS can fall out of favour because of this.
my answer didn't seem to make by email:
Agree with the link – Eawag have done a lot of work on SODIS. Helvetas Swiss Intercooperation probably have the most experience with testing and implementing SODIS in their projects.
RWSN doesn’t do much in this area because it falls within the scope of the Household Water Treatment Network - http://hwts.web.unc.edu/ so they are good source of expertise on SODIS and others.
from the latter:
Advantages • Improves the microbiological quality of drinking water and therefore health • Extremely low-cost • Easy to understand and simple to use • Relies on locally available resources, plastic bottles and sunlight, a renewable energy source Disadvantages • Does not treat chemical pollution • Is strongly climate and weather dependent • Only small volumes can be treated at a time and regardless the simplicity, it is relatively time-consuming to cover the entire water consumption of a household with SODIS • Requires the availability of PET bottles (or plastic bags) • Needs large efforts in terms of promotion and information to have an impact
There has been some discussion about the health effects of using PET because of concerns (mainly in the US) about leaving water bottles in cars leading to some plastic contamination of the water. However, Eawag counter that in the SODIS context, the health risk from the plastic is orders of magnitude lower than the health risks associated with drinking microbially contaminated water. No magic bullets….
Agree with most of the posts. Good resources. Recommend testing the water source before, and after SODIS "treatment", for e.coli, coliform, and any other lab tests available. NGO did local testing on stream and shallow well water, treated with SODIS for 24 and 48 hours, and found substantial numbers of bacteria still present. So bio risk may be improved, but not eliminated ... thus may not meet WHO guidelines of 1-4 colonies.
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