Interventions to improve water quality, particularly when implemented at the household level, are effective in preventing diarrhoea in settings where it is endemic

Diarrhoea is a major cause of death and disease, especially among young children in low-income countries. Loss of fluid (dehydration) is the major threat, though diarrhoea also reduces the absorption of the nutrients, causing poor growth in children, reduced resistance to infection, and potentially long-term gut disorders. This review examined trials of interventions to improve the microbiological quality of drinking water. These include conventional improvements at the water source (eg protected wells, bore holes, and stand posts) and point-of-use interventions at the household level (eg chlorination, filtration, solar disinfection, and combined flocculation and disinfection). The review covered 38 independent comparisons from 30 trials that involved more than 53,000 people. In general, such interventions were effective in reducing episodes of diarrhoea. Household interventions were more effective in preventing diarrhoea than those at the source. However, differences in the interventions and the settings in which they were introduced, as well as the methods and measurements of effect, limit the extent to which generalizations can be made. Further research, including blinded trials and longer-term assessments, is necessary to understand the full impact of these interventions.