Health Literature Summary - Issue 50 - June 2008

Difficulties in bringing point-of-use water treatment to scale in rural Guatemala.
Luby, S.P., Mendoza, C., Keswick, B.H., Chiller, T.M. and Hoekstra, R.M. (2008) American Journal of Tropical Medicine & Hygiene, 78(3); 382-7.

Point-of-use water treatment has been shown to be the most cost-effective approach to reduce the number of person who do not have access to safe water. A flocculant-disinfectant treatment combining precipitation, coagulation and flocculation with chlorination has been developed for household use in developing countries. Two health outcome efficacy studies of this flocculant-disinfectant were conducted in Guatemala between 2001 and 2003. The first study found that children in households assigned to receive the flocculant-disinfectant had 25-29% fewer days of diarrhoea even though the use of the product was suboptimal. The second study used a modified form of the flocculant-disinfectant with a lower dose of chlorine to improve taste. Those in households receiving the intervention reported 39% fewer days of diarrhoea compared to control households. Three weeks after the end of the second health outcome efficacy study, an intensive marketing campaign for the flocculant-disinfectant was conducted in the region. A single sachet of the flocculant-disinfectant sufficient to treat 10 L of water retailed for US$0.14. Six months later the study population was investigated to assess purchase and use of the flocculant-disinfectant.

There were 462 of the 514 households in the efficacy study who completed a follow-up evaluation. All except one household reported using the flocculant-disinfectant at least once and 388 (84%) reported that use of the flocculant-disinfectant improved the taste of their water. However only 66 households (14%) reported using the flocculant-disinfectant in the preceding week and only 34 (7%) had bought the flocculant-disinfectant more than six times. Only 22 households (5%) met the criteria for active repeat use (reported purchasing the product within the last 2 weeks, using it within the previous week and having at least one unopened sachet in the household observed) and only 7 households (1.5%) had detectable chlorine in their drinking water. Of the 22 households that met the criteria for active repeat use, only 4 (18%) had detectable chlorine in their drinking water at the study visit. The only characteristics that were associated with becoming an active repeat user were a stated belief that the household's drinking water was dirty and a belief that the household drinking water made the family ill. However households that became active repeat users had a similar proportion of child days of diarrhoea during the study period in their households compared with household that did not become active repeat users (2.9% versus 2.7%, P=0.73).

The flocculant-disinfectant is largely effective in treating drinking water however there are multiple barriers to moving from technical efficacy to public health effectiveness in populations lacking access to safe drinking water. If these interventions are going to contribute substantially to reduce the number of people whose drinking water is contaminated, then future research efforts are required to assess and improve the effectiveness and sustainability of large-scale point of use water treatment interventions.