Diseases caused by drinking dirty water are major causes of health problems in developing countries.  Approximately four billion cases of diarrhoea in the year 2000 represent more than 5% of all disease globally for that year. The problem is not only water containing bacteria at its source, but often clean water that becomes contaminated between its source and the point at which it is drunk.  This is a serious problem which can undermine government health campaigns to provide every home with clean water.

A common strategy for dealing with dirty water is to provide villages with protected water sources such as boreholes, standpipes or wells.  However these are often some distance from people’s homes and the water must then be collected, transported and stored in the home.  By the time the water is drunk it is often of a much poorer quality than it was at its source.  The water may have been contaminated by dirty hands, unwashed storage containers and dippers.  The University of Bristol, together with the Royal College of Surgeons in Ireland, looked at the extent of the problem by analysing 57 studies into water contamination between its source and use.

The studies, which took place in 30 different countries around the world, all looked at three types of bacteria:  total coliforms, faecal coliforms and E coli.  E coli bacteria which originate from faeces are now recognised as the most reliable proof of public health risks in drinking water.  Total coliforms can enter water from rotting vegetation, and faecal coliforms, contrary to their name, may not originate from faeces.

The research found that in half of the communities studied, the quality of drinking water fell noticeably after it was collected. The research also found that:

• There were no communities studied where water quality improved after collection and storage.
• Contamination was more noticeable in communities that used safe water sources, such as standpipes or boreholes.
• The reasons for water becoming contaminated varied from study to study.
• A common cause of contamination was scooping up water from uncovered vessels with unwashed cups or hands.
• In other studies in the review, contamination was affected by a lack of basic sanitation, using different pots for carrying and storing water, the way water was drawn at the source, and using earthenware pots as water containers.

The researchers note that caution may be necessary as the studies’ findings may be biased by people’s behaviour.  Once they realise their behaviour is under observation they may become more careful in the way they handle water.  Additionally, people may be reluctant to admit to researchers that they use an unprotected water source close to their home rather than covering the longer distance to collect clean water.  If the water they collect is already contaminated this will obviously affect the studies’ findings and make post-collection contamination appear greater than it is reality.

In addition to providing a protected water source the report recommends:

• safer household water storage and treatment
• monitoring the quality of the water in the home to give a better idea of whether people are drinking clean water
• finding ways to prevent contamination in the home.

Improving the quality of the water at its source is not enough because contamination is widespread during collection, transport, storage and drawing of the water.  If government health programmes for clean water are not to be undermined, action must be taken to educate people about basic hygiene within the home.

Source(s):
‘Household drinking water in developing countries:  a systematic review of microbiological contamination between source and point-of-use’, Tropical Medicine and International Health 9(1): 106-117, by J. Wright, S. Gundry and R. Conroy, 2004
HINARI subscribers can access the full-text article here. Full document.

Funded by: The European Union INCO-DEV programme

id21 Research Highlight: 10 June 2004

Further Information:
Jim Wright
Dept of Geography
University of Southampton
Shackleton Building
Highfield
Southampton SO17 1BJ
UK

Tel: +44 (0) 2380 594619
Fax: +44 (0) 2380 593295
Contact the contributor: J.A.Wright@soton.ac.uk

University of Bristol, UK

Contact the contributor: aquapol-info@bristol.ac.uk

Royal College of Surgeons, Ireland

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'Waiting at the tap: deteriorating urban water supply in East Africa'

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