The cost of dirty water

Posted: 17 January 2001

Author: John Bland

The health consequences of dirty water are so all-pervading that they defy efforts to draw up a global balance-sheet. Take Peru: in the first 10 weeks after a cholera epidemic broke out in the early 1990s, the World Bank estimated losses from reduced agricultural exports and tourism at US $1,000 million - over three times what the country had invested in water supply and sanitation services during the 1980s.

Yet the most common water disinfectant, chlorine, is very effective against Vibrio cholera, and if readily available would cost an average family between 25 cents and $2 per year. According to WHO, ensuring safe water supply and sanitation throughout Latin America - the long-term answer to cholera - calls for a total capital investment of some $5,000 million a year over the next 10 years. Cholera is only one of a great many waterborne or water-related illnesses. The diarrhoeal diseases alone kill about four million people a year, of whom 80 per cent are children. Many of those lives could he saved by treatment with oral rehydration salts - ORT - which are made widely available in the Third World by international agencies and cost as little as 20 per cent per treatment. In one year alone, almost 40 per cent of cases of diarrhoea in children were treated with ORT, averting about one million unnecessary deaths. On the other hand, WHO estimates that each year between $1,000 and $2,000 million are wasted on inappropriate treatment of diarrhoea and respiratory infections.

African challenge

In Sub-Saharan Africa alone, the indirect cost of malaria - a waterborne disease since the vector mosquito breeds in stagnant pools - was estimated to exceed US$1,800 million in 1995. Worldwide, an estimated two million people die from malaria every year, including more than a million young children, a large proportion of them in Africa¹. The cost must be measured both in lives lost and in working hours lost through illness. Community campaigns can be effective in destroying standing pools of water where the mosquitoes breed that transmit malaria to humans. But government expenditure is crucially needed to foster such campaigns, to underline the value of impregnated bed nets and to provide medical treatment.

Then there is schistosomiasis, transmitted by a watersnail living in standing water where humans work, play - and urinate. Found in 76 countries, this disease kills some 200,000 people every year but debilitates another 200 million, thereby putting a serious brake on each country's economic advancement. Data from both field and laboratory studies indicate that climate change would affect the parasite's cycle. watersnailWatersnail which carries the parasite causing schistosomiasis© Mark Edwards/IPPFTemperature influences watersnail reproduction and growth, schistosomiasis mortality, infectivity and development of the parasite within the snail, and human-to-water contact. If temperatures increase, snails may promote schistosomiasis transmission over a longer period during the year².

Onchocerciasis has long plagued huge tracts of West Africa, yet today it has been virtually removed from the original seven Onchocerciasis Control Programme countries in West Africa. Thirty million people are protected from infection from the bites of the blackfly which breeds in rivers and streams - hence the common name of the disease, river blindness. The main goal of the current OCP is to obtain complete interruption of transmission so as to have only minimal residual control activities by 2002, with no new foci of infection in the controlled areas³.

Transmitted by drinking water containing a parasite, guinea worm disease causes painful blisters, usually on the leg, preventing the victims from working or - in youngsters - from attending school. The economics of this disease must take into account its effects on the health, agriculture and education in endemic areas. Merely to filter drinking water is a cost-effective means of preventing guinea-worm and WHO has been working with governments and NGOs in an effort to wipe out this disease. Although cases have fallen from one million in 1989 to fewer than 90,000 in 1999 (66 per cent of which were notified in Sudan), total eradication has proved elusive 4.

Few developing countries seem willing to draw up a simple balance sheet. On one side, the human and financial cost of water-related diseases in terms of lives lost and man-hours of work wasted; and on the other side, the expense of ensuring clean water and proper sanitation for all citizens. Undoubtedly, the first column would prove costlier.

John Bland is former Editor of WHO's magazine World Health.

Climate Change and Human Health, WHO/WMO/UNEP, 1996, page 78.

Climate Change and Human Health, WHO/WMO/UNEP, 1996, page 93.

3. WHO website

4. WHO