Tropical Medicine and International Health
volume 7 no 9 pp 750–756 september 2002
J. K. Tumwine et al. Diarrhoea and effects of different water sources
The issues
The original Drawers of Water (White et al. 1972) study
distinguished between four alternative means of transmission of water-related diseases: water-washed, water-borne,
water-based and by water-related insect vectors. Since then
there has been a great deal of emphasis on water and sanitation improvement to reduce transmission by these routes.
In a review of more than 60 studies, Esrey et al. (1985)
found that the median benefits of service improvements in
reducing diarrhoea morbidity were 25% from improved
water availability, 22% from improved excreta disposal,
and 16% from water quality improvements.
But controversy still rages in this area with several
consultants questioning the role of water improvements in
reducing diarrhoea morbidity. In a cross-sectoral analysis
involving eight countries (including Uganda), Esrey (1996)
found that sanitation improvements conferred much larger
benefits than water improvements. In Indonesia, Wibowo
and Tisdell (1993) provided additional evidence of the
efficacy of water and sanitation in improving health status.
In a review of 29 studies of diarrhoea prevalence in
Uganda, Burton and Wamai (1992) found that the prevalence of diarrhoea, in the 2 weeks preceding the surveys,
was 8.6–19.5%. Higher rates of diarrhoea were associated
with unprotected sources of water and lack of latrines. In
the light of studies such as these, considerable effort has
gone into the development of improved water supply and
sanitation facilities. However, despite investments in water
and sanitation programmes, the population with access to
safe water in East Africa remains low as shown in Table 1,
which lists WHO/UNICEF figures for service coverage in
1990 and 2000 (WHO/UNICEF 2000). Indeed, in some
cases estimated coverage has fallen: the urban water supply
in Kenya and Uganda and rural sanitation in Uganda have
deteriorated. Changes in total coverage are also affected by
the increasing urban population. Almost 42 million people
in the three countries do not have access to ÔimprovedÕ
water supply and 13 million do not have access to
ÔimprovedÕ sanitation facilities.
Sanitation service coverage is generally defined as the
proportion of the population with access to Ôat least
Table 1 Water supply and sanitation
coverage in East Africa 1990 and 2000
adequate excreta disposal facilities that can effectively
prevent human, animal and insect contact with excretaÕ.
Suitable facilities range from simple but protected pit
latrines to flush toilets with sewerage (WHO 1996). Water
supply coverage refers to the proportion of the population
with adequate access to safe drinking water in a dwelling
or located within a convenient distance from the user’s
dwelling. Reasonable access implies that the housewife
does not have to spend a disproportionate part of the day
fetching water for the family’s needs; 200 m is regarded as
a convenient distance (Rosen & Vincent 1999).
In recent years, the historical emphasis on water and
sanitation facility improvements to reduce the transmission
of diarrhoeal diseases has shifted, or rather been complemented, by increased attention given to the effects of
hygiene behaviour rather than service improvements per se
(Kolsky 1993; Varley et al. 1998). In policy terms, some of
the emphasis has shifted to promotion of hygiene behaviour
rather than service improvements alone (Kolsky 1993;
Esrey 1996). Personal hygiene programmes tend to reduce
transmission of water-washed diseases (spread through
inadequate personal hygiene) and possibly water-borne
diseases (spread through contaminated water) as well.
This study has given us the opportunity to explore the
relative importance of different means of transmission of
water-related diseases, particularly diarrhoea. The extensive nature of the Drawers of Water (DOW II) survey
allows for an analysis of the relative importance of
different transmission routes, and thus the effectiveness of
different policy interventions. The results relating to water
source choice and access and water use have been
published elsewhere (Thompson et al. 2002). This paper
sheds light on the possible effects of water and sanitation
use patterns, and some aspects of hygiene behaviour, on
the prevalence of diarrhoea in Kenya, Tanzania and
Uganda.
Materials and methods
The data and results presented in this paper are based upon
a survey of households in East Africa. The survey was
carried out in 1997 in the 33 East African sites studied in
Water supply coverage in 2000
(1990 in parentheses)
Sanitation service coverage in 2000
(1990 in parentheses)