Proceedings of the International Symposium on Efficient Water Use in Urban Areas

Dr G Goldstein
Coordinator, Healthy Cities Programme, Department of Health Promotion, WHO

We see every day increasing competition for water among alternative uses: in industry, agriculture, wildlife and protection of natural resources, urban development, environmental quality, and last but not least human health. Everywhere there are indications of this competition, for example in northern Nigeria water diverted for irrigation leads to loss of livelihood for people downstream, or in India a falling water table threatens the loss of water resources for a peri-urban community. As a result of the competition, we can no longer address water planning and management on a project-by-project basis; increasingly we must integrate water resource use across different users and across different economic sectors. Whilst agriculture is frequently highlighted as using an overall 70 per cent of abstracted water and as being typically very inefficient, it is likely that irrigated agriculture will be extended to meet future food demands - substantial water savings within the sector are therefore unlikely. Other potential approaches to relieve volumetric demands exist – most representing some form of demand displacement through use of locally-captured water, or waste water re-use in urban green space or peri-urban agriculture. Many approaches raise new questions concerning their health impact.

In my talk today I would like to examine one key aspect of the water-health relationship – faeco-oral transmission of disease. I will try to explain why we have failed to break this transmission, and propose a solution to this issue. I will argue that efficient water use requires attention to breaking faeco-oral transmission of disease as an integral part of water management, and discuss how WHO is addressing this issue.

First I would like to look briefly at this idea of efficient water use. The economic efficiency of water use is measured in terms of the economic benefits of each use, less its costs. However in a given water management scheme, who gains and who loses may not be part of the efficiency criterion per se. Because of the externalities inherent in water development projects there are almost always winners and losers. Upstream users may pollute rivers with wastes or choke them with sediment, causing severe damages to downstream users. Local people lose their lands in a dam project, so that urban populations can have electric power and lowland farmers can have irrigation. Irrespective of efficiency, the health impacts of displacement – relocation or resettlement – are frequently severe. Many examples of dams that were justified on the grounds of efficient water use have not considered the costs to the displaced persons from inundated land, or the loss of livelihood that results for people downstream (Acreman, 1996). Another common conflict occurs between surface and groundwater users in irrigated agriculture. Improvement in the efficiency of application of the surface water results in a decline in the availability of groundwater.

I propose that models of efficient water use integrate inputs, outputs and impacts across different users and across different economic sectors, and in particular include health impacts. How one might approach the task to develop such an integrated model? I would propose several premises: that a given category of water use, use that leads to a health benefit is more efficient than water use that fails to achieve a potential health benefit; and that the efficiency of health interventions in relation to water and sanitation projects should be judged “cost-effective” or economical in terms of measurable outcomes produced by money spent. Cost-effectiveness of an intervention can be evaluated with a cut-off or test value. For example, an intervention to reduce diarrhea with a cost-effectiveness of less than $100/DALY would be considered cost-effective (Varley 1995).

Rogers (1992) has pointed out that a relationship between water and health has been accepted since at least the time of Frontinus, the Water Commissioner of Rome in AD 97, however the details still present challenges. More recently in 1990 the Global Burden of Disease Study provided the public health community with a set of consistent estimates of disease and injury rates (Murray and Lopez, 1996). A glance at the global burden of disease shows us that even after 2 millennia, diarrheal disease is still prevalent, and the faeco-oral route of disease transmission continues to confound health authorities (Table 1).

The “global burden of disease” that is attributable to deficient water and sanitation, and personal and domestic hygiene - and another 9 major identifiable risk factors included in the table on the basis of major impact on the disease burden - is set out in Table 1.

YLL Years of Life Lost;
YLD Years lived with Disability (adjusted for severity of disability),
DALY Disability Adjusted Life Year

Table 1:Global Burden of Disease and Injury Attributable
to Selected Risk factors, 1990
Risk Factor	Deaths (thousands)	As % of total Deaths	YLLs (thousands)	As % of total YLLs	YLDs (thousands)	As % of YLDs	DALYs (thousands)	As % of total DALYs
Malnutrition	5881	11.7	199486	22.0	20089	4.2	219575	15.9
Poor water supply, Sanitation and personal and domestic hygiene	2668	5.3	85520	9.4	7872	1.7	93392	6.8
Unsafe sex	1095	2.2	27602	3.0	21100	4.5	48702	3.5
Tobacco	3038	6.0	26217	2.9	9965	2.1	36182	2.6
Alcohol	774	1.5	19287	2.1	28400	6.0	47687	3.5
Occupation	1129	2.2	22493	2.5	15394	3.3	37887	2.7
Hypertension	2918	5.8	17665	1.9	1411	0.3	19076	1.4
Physical Inactivity	1991	3.9	11353	1.3	2300	0.5	13653	1.0
Illicit drugs	100	0.2	2634	0.3	5834	1.2	8467	0.6
Air Pollution	568	1.1	5625	0.6	1630	0.3	7254	0.6

As a major risk factor or hazard to health, water and sanitation ranks second only to malnutrition in its impact on the disease burden (Table 1). In the case of water and sanitation, (and malnutrition), virtually the entire burden is borne by the poor, with only 0.1% of the YLL’s in developed regions and 10.4% in developing regions. This compares for other risk factors in the table, such as tobacco use, which has 16.2% of the total YLLs in developed regions and only 1.5% in developing regions.

I will now focus on the faecal-oral route of disease transmission as the key “water-health issue”. Of course there are other categories of water-related disease, (including chemical contamination of water supplies, e.g. the arsenic problem in Bangladesh and other countries, or problems of mosquitoes that are disease vectors breeding in stagnant pools of water where neighborhoods lack adequate surface water drainage). However in terms of the global burden, other water-related diseases are much less important.

Faecal-oral diseases occur when faeces from a person infected with the disease enters the mouth of another person. The pathogens contained in the faeces may be transmitted to hands, water or food, and water or food is then ingested by another person. Different faecal-oral diseases include diarrhoea, dysentery, cholera, giardia, typhoid, infectious hepatitis and intestinal worms. In understanding approaches to interrupt the faeco-oral route, we may consider this model:

We see there are three factors or determinants on the left hand side of the model, needed to secure health. A deficiency of any one factor may lead to disease. While all three are complex, and inter-related, it will be argued that combining infrastructure with good hygiene practice is a highly cost-effective option in water management, and is integral to efficient water use.