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As discussed yesterday, the WASH cluster in Rakhine is concerned about the usage of ceramic filters with chlorinated water and we would like to have your support to be able to make the most appropriate recommendations. We definitely agree with you that the standard process implies filtration prior to disinfection. However, in Rakhine the context is such that we may have to chlorinate before filtration. Indeed, Households have received or will receive soon ceramic water filters. In the eventuality of an acute watery diarrhea outbreak (or suspicion of outbreak), the WASH Cluster believes that systematic chlorination of the drinking water is mandatory to contain the contamination; potentially the duration of the chlorination would cover the rainy season (6 months).

The two issues that we would like to clarify are : - The ceramic filters are silver coated. The chlorine being a strong oxidant, there is a risk that the silver is oxidized and released in the water with 2 consequences: loading the drinking water with Ag+, reducing the coating of the filter and therefore its efficiency. - The filter will collect organic material at its surface, even if the water is clear, there will always be some residue. The chlorine contained in the water would preferably react with those to create toxic sub-products such as haloforms or chloropenols.

Therefore, the support that we would need is : - to confirm or correct those issues identified, as those are issue from educated guess rather than extensive research - if confirmed, provide some expertise on evaluating the impact of those problems in public health : the levels of sub-products and Ag+ that can be reached, impact of ingestion of those over 6 months, … Change of filters systematically after ending the chlorination?

Some additional information that may help : The protected water sources in the camps are various : handpumps, pondwater treated through a water treatment unit, piped networks. The average turbidity of those sources ranges from 30 NTU to less than 5NTU.
The chlorine level targeted is 0,2 – 0,5mg/l. However, experience shows that it can reach 1mg/l when camp-based teams are not closely supervised (which happens quite often during rainy season due to weather condition in some remote townships).

I hope that this is clear, if not just let me know.

Thanks for your support

As discussed yesterday, the WASH cluster in Rakhine is concerned about the usage of ceramic filters with chlorinated water and we would like to have your support to be able to make the most appropriate recommendations. We definitely agree with you that the standard process implies filtration prior to disinfection. However, in Rakhine the context is such that we may have to chlorinate before filtration. Indeed, Households have received or will receive soon ceramic water filters. In the eventuality of an acute watery diarrhea outbreak (or suspicion of outbreak), the WASH Cluster believes that systematic chlorination of the drinking water is mandatory to contain the contamination; potentially the duration of the chlorination would cover the rainy season (6 months).

The two issues that we would like to clarify are : - The ceramic filters are silver coated. The chlorine being a strong oxidant, there is a risk that the silver is oxidized and released in the water with 2 consequences: loading the drinking water with Ag+, reducing the coating of the filter and therefore its efficiency. - The filter will collect organic material at its surface, even if the water is clear, there will always be some residue. The chlorine contained in the water would preferably react with those to create toxic sub-products such as haloforms or chloropenols.

Therefore, the support that we would need is : - to confirm or correct those issues identified, as those are issue from educated guess rather than extensive research - if confirmed, provide some expertise on evaluating the impact of those problems in public health : the levels of sub-products and Ag+ that can be reached, impact of ingestion of those over 6 months, … Change of filters systematically after ending the chlorination?

Some additional information that may help : The protected water sources in the camps are various : handpumps, pondwater treated through a water treatment unit, piped networks. The average turbidity of those sources ranges from 30 NTU to less than 5NTU.
The chlorine level targeted is 0,2 – 0,5mg/l. However, experience shows that it can reach 1mg/l when camp-based teams are not closely supervised (which happens quite often during rainy season due to weather condition in some remote townships).

I hope that this is clear, if not just let me know.

Thanks for your support