Interventions to improve water quality and prevent diarrhoea

A new Cochrane evaluates trials of interventions to improve water quality. It included 55 studies and >84,000 participants. Most were conducted in low- or middle-income countries  (50 studies), with unimproved water sources (30 studies), and unimproved or unclear sanitation (34 studies).

On average, distributing disinfection products for use in the home may reduce diarrhoea by around one quarter in the case of chlorine products (low quality evidence), and around a third in the case of flocculation and disinfection sachets (moderate quality evidence). Water filtration at home probably reduces diarrhoea by around a half (moderate quality evidence), and effects were consistently seen with ceramic filters (moderate quality evidence), biosand systems (moderate quality evidence) and LifeStraw® filters (low quality evidence). Plumbed-in filtration has only been evaluated in high-income settings (low quality evidence). In low-income settings, distributing plastic bottles with instructions to leave filled bottles in direct sunlight for at least six hours probably reduces diarrhoea by around a third (moderate quality evidence).

Overall the authors concluded that point-of-use interventions may be important interim measures to improve drinking water quality until reliable, in home, piped-in water connections are available. Comparisons between estimates do not provide evidence of superiority of one intervention over another, as such comparisons are confounded by study setting, design, and population. 

The review can be found at http://www.cochrane.org/CD004794/INFECTN_interventions-improve-water-quality-and-prevent-diarrhoea