23 July 2007

Health impact of water and sanitation interventions

Q: Could you advise me on the latest research on the health impacts of WSS interventions particularly water quality, water quantity, sanitation and hygiene?
(Ministry of Agriculture and Rural Development, Viet Nam)


"The impact of sanitation on human health is the most widely recognised benefit of good sanitation and hygiene practices.”

This is taken from the Thematic Overview Paper (TOP) Enhancing livelihoods through sanitation. (2007). By Borba, M.L., Smet, J. and Sijbesma, C.

The figures in Table 1 below confirm this.

Table 1. The impact of sanitation, water and hygiene on morbidity by diarrhoea

Water and Sanitation measures and % decrease in cases of diarrhoea:

Water and sanitation 30
Sanitation (improved excretal disposal) 36
Improved hygiene 33
Quantity of water 20
Water quantity and quality 17
Water quality 15

It is clear from these data, that when sanitation is taken by itself, health improves at a higher level than through provision of water alone. The same can be said about hygiene interventions.

See also Section 5 of the same TOP: Stories from the field: a review of practices presents case-studies from Asia, Africa and Latin America, where efforts are made to improve human excreta management and their impact on people’s livelihoods.

In a working paper of the Harvard University Centre for International Development, Alix Peterson Zwane and Michael Kremer review the research on what works in preventing and treating diarrheal diseases in developing countries. They review the evidence on individual behavior change interventions that can prevent diarrhea, including handwashing and point-of-use water treatment systems.

The paper also discusses the outstanding question of how to induce people to adopt these methods. It then reviews the evidence on the effectiveness of source water quality improvements and sanitation investments.

Rural infrastructure maintenance is another challenge being discussed in their article: while rural water facilities can be long-lived if properly serviced, they often fall into disrepair quickly due to poor maintenance, and though many different approaches to maintenance have been advocated, there is little evidence on their relative effectiveness.

Another document by Guy Howard and Jamie Bartram, entitled Domestic water quantity, service level and health, describes the relationships between water, sanitation hygiene and diarrhoea as well as other infectious diseases, such as trachoma.

“Despite the evidence pointing to the benefits of increased quantities of water on health, the relationship is not simple and most research has made significant assumptions about water use. Hygiene is not solely related to availability of water, but also to specific hygiene behaviours such as hand washing at critical times, for instance before eating and cooking and after defecation.”

And “A number of studies suggest that hand washing with soap is the critical component of this behaviour and that hand washing only with water provides little or no benefit (Cairncross, 1993; Ghosh et al., 1997; Khan, 1982; Oo et al., 2000). Hoque and Briend (1991) showed that whilst less effective than when using a rubbing agent, such as soap, mud or ash, some reductions in contamination were found when washing with water alone, but that use of alternative rubbing agents (mud or ash) provided the same benefits as soap. Hoque et al. (1995) also found that use of mud, ash and soap all achieved the same level."

Read the full documents yourself:

Peterson Zwane, A. and Kremer, M. (2007). What works in fighting diarrheal diseases in developing countries? (CID Working Paper No. 140). Cambridge, United Kingdom, Harvard University. Available at: http://www.cid.harvard.edu/cidwp/pdf/140.pdf

Howard, G. and Bartram, J. (2003). Domestic water quantity, service level and health. Geneva, Switzerland, World Health Organization. Available at: http://www.who.int/water_sanitation_health/diseases/wsh0302/en/

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