We evaluated the ability of UNICEF-designed pot-chlorinators to achieve recommended free residual chlorine (FRC) levels in well water in Bissau, Guinea-Bissau, during a cholera outbreak. Thirty wells were randomly selected from six neighbourhoods. Pot-chlorinators – perforated plastic bottles filled with gravel, sand and calcium hypochlorite granules – were placed in each well. FRC was measured before and 24, 48 and 72 h after placement and compared with World Health Organization (WHO)-recommended levels of ≥1 mg L−1 for well water during cholera outbreaks and 0.2–5 mg L−1 in non-outbreak settings. Presence of well covers, distance from wells to latrines, and rainfall were noted. Complete post-chlorination data were collected from 26 wells. At baseline, no wells had FRC >0.09 mg L−1. At 24, 48 and 72 h post-chlorination, 4 (15%), 1 (4%) and 0 wells had FRC ≥1 mg L−1 and 16 (62%), 4 (15%) and 1 (4%) wells had FRC between 0.2 and 5 mg L−1, respectively. Several families reported discontinuing household water chlorination after wells were treated with pot-chlorinators. Pot-chlorinators failed to achieve WHO-recommended FRC levels in well water during a cholera outbreak, and conveyed a false sense of security to local residents. Pot-chlorination should be discouraged and alternative approaches to well-water disinfection promoted.
Evaluation of pot-chlorination of wells during a cholera outbreak, Bissau, Guinea-Bissau, 2008
Elizabeth C. Cavallaro, Julie R. Harris, Mauricio Serafim da Goia, Jean Carlos dos Santos Barrado, Aglaêr Alves da Nóbrega, Inácio Carvalho de Alvarenga Júnior, Augusto Paulo Silva, Jeremy Sobel, Eric Mintz; Evaluation of pot-chlorination of wells during a cholera outbreak, Bissau, Guinea-Bissau, 2008. J Water Health 1 June 2011; 9 (2): 394–402. doi: https://doi.org/10.2166/wh.2011.122
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