Interventions to improve water quality for preventing diarrhoea


Thomas F. Clasen1, Kelly T. Alexander1, David Sinclair2, Sophie Boisson3, Rachel Peletz4, Howard H. Chang5, Fiona Majorin3, Sandy Cairncross6

1. Rollins School of Public Health, Emory University, Department of Environmental Health, Atlanta, GA, USA
2. Liverpool School of Tropical Medicine, Department of Clinical Sciences, Liverpool, UK
3. London School of Hygiene & Tropical Medicine, Faculty of Infectious and Tropical Diseases, London, UK
4. Aquaya Institute, Nairobi, Kenya
5. Rollins School of Public Health, Emory University, Department of Biostatistics and Bioinformatics, Atlanta, GA, USA
6. London School of Hygiene & Tropical Medicine, Department of Disease Control, Faculty of Infectious and Tropical Diseases, London, UK

To read the full text article, please follow this link: DOI:10.1002/14651858.CD004794.pub3/full

This Cochrane Review summarizes trials evaluating different interventions to improve water quality and prevent diarrhoea. After searching for relevant trials up to 11 November 2014, we included 55 studies enrolling over 84,000 participants. Most included studies were conducted in low- or middle-income countries (LMICs) (50 studies), with unimproved water sources (30 studies), and unimproved or unclear sanitation (34 studies).

What causes diarrhoea and what water quality interventions might prevent diarrhoea?

Diarrhoea is a major cause of death and disease, especially among young children in low-income countries where the most common causes are faecally contaminated water and food, or poor hygiene practices.

In remote and low-income settings, source-based water quality improvement may include providing protected groundwater (springs, wells, and bore holes) or harvested rainwater as an alternative to surface sources (rivers and lakes). Alternatively water may be treated at the point-of-use in people's homes by boiling, chlorination, flocculation, filtration, or solar disinfection. These point-of-use interventions have the potential to overcome both contaminated sources and recontamination of safe water in the home.

What the research says

There is currently insufficient evidence to know if source-based improvements in water supplies, such as protected wells and communal tap stands or treatment of communal supplies, consistently reduce diarrhoea in low-income settings (very low quality evidence). We found no trials evaluating reliable piped-in water supplies to people's homes.

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 before drinking probably reduces diarrhoea by around a third (moderate quality evidence).

Research assessing the effects of household connections and chlorination at the point of delivery will help improve our knowledge base. Evidence indicates the more people use the various interventions for improving water quality, the larger the effects, so research into practical approaches to increase coverage and help assure long term use of them in poor groups will help improve impact.