Water Supply and Health
Citation: Hunter PR, MacDonald AM, Carter RC (
Water Supply and Health
Paul R. Hunter 0 1 2
Alan M. MacDonald 0 1 2
Richard C. Carter 0 1 2
0 Abbreviations: DALY, disability-adjusted life year; GDP, gross domestic product; JMP, WHO/UNICEF Joint Monitoring Programme for Water-supply and Sanitation; MDG, Millennium Development Goal; NGO , nongovernmental organization; WSP , Water Safety Plan
1 Competing Interests: PRH is chair of the board of directors of the Institute of Public Health and Water Research, Texas A & M University; chairs the science advisory council for Suez Environment; and has done consultancy work for Danone bevarages. Neither of the other two authors have any competing interests to declare
2 1 School of Medicine , Health Policy and Practice , University of East Anglia , Norwich , United Kingdom , 2 British Geological Survey, Edinburgh , United Kingdom , 3 WaterAid, London , United Kingdom
A safe, reliable, affordable, and easily
accessible water supply is essential for good
health. Yet, for several decades, about a
billion people in developing countries have
not had a safe and sustainable water supply.
It has been estimated that a minimum of
7.5 litres of water per person per day is
required in the home for drinking,
preparing food, and personal hygiene, the most
basic requirements for water; at least
50 litres per person per day is needed to
ensure all personal hygiene, food hygiene,
domestic cleaning, and laundry needs .
This domestic water consumption is
dwarfed by the demands of agriculture
and ecosystems, even in wealthy countries
where per capita domestic water
consumption greatly exceeds these figures . To
cover all these requirements and to avoid
water stress, experts generally agree that
about 1,000 cubic metres of freshwater per
capita per year is needed .
A key target of Millennium Development
Goal (MDG) 7, which aims to ensure
environmental sustainability, is to reduce
by half the proportion of people without
sustainable access to safe drinking water and
basic sanitation by 2015 . This water
supply target underpins several other
MDGs, including those relating to poverty
(MDG1), education (MDG2), and gender
equality (MDG3). In particular, it underpins
MDG4, the reduction of child mortality,
because many deaths in young children in
developing countries are due to diarrhoeal
disease, and unsafe water is a key risk factor
for diarrhoeal disease in this age group .
The WHO/UNICEF Joint Monitoring
Programme for Water-supply and
Sanitation (JMP), which monitors progress on
the MDG water supply target, identifies
The Policy Forum allows health policy makers
around the world to discuss challenges and
opportunities for improving health care in their
three categories of drinking water supply:
(a) water piped into the dwelling, plot, or
yard; (b) other improved sources (including
public taps, protected springs, hand
pumps, and rainwater harvesting); and (c)
unimproved sources (open water,
unprotected from contamination) . JMP
assumes that improved water should be
available not only for drinking but also for
food preparation and personal and home
hygiene, but it provides no official
definition of how near a water source should
be to a dwelling to be called improved.
However, a distance of ,1,000 m has been
suggested as an appropriate distance for
meeting the MDG targets .
In poorly served countries, achieving the
MDG water supply target will involve
increasing water availability for domestic
uses, improving water quality, and
bringing about changed water-use and
watermanagement habits. In the wealthy
countries where adequate quantities of domestic
water are already available on demand, the
main task over the next few years will be to
sustain water quality given the increasing
pressures of pollution. However, global
water supply targets need to be tempered
by a recognition of the real demand (as
expressed in user willingness and ability to
pay), which may be less ambitious than the
internationally agreed target. Furthermore,
account needs to be taken of the realities
of frequently poor levels of functionality.
It is relatively easy to increase coverage
through construction of water supply
systems, but it is much more difficult to
ensure that such systems continue to
provide service over the long term.
We therefore argue in this paper for a
serious commitment by national
governments and their partners to ensure
adequate water supply services for all (the
MDG target, if met, would still leave 672
million people with an unimproved supply
[6,8]). In addition, we call for increased
attention to be paid to ensuring continuing
service provision. This will mean finding
new ways to enhance public demand for
improved services (that might translate
into a willingness to pay), and a public and
private sector ethos that puts high value on
the quality of construction and ongoing
Water Supply and Health
Inadequacies in water supply affect
health adversely both directly and
indirectly (Box 1 and below). An inadequate
water supply also prevents good sanitation
and hygiene. Consequently, improvements
in various aspects of water supply
represent important opportunities to enhance
public health. Box 2 lists six attributes of
domestic water supply that determine
whether it is effective in the preservation
of good health .
N A safe, reliable, affordable, and easily accessible water supply is essential for
good health, but for several decades almost 1 billion people in developing
countries have lacked access to such a supply.
N A poor water supply impacts health by causing acute infectious diarrhoea,
repeat or chronic diarrhoea episodes, and nondiarrhoeal disease, which can
arise from chemical species such as arsenic and fluoride. It can also affect health
by limiting productivity and the maintenance of personal hygiene.
N Reasons for the limited progress towards universal access to an adequate water
supply include high population growth rates in developing countries,
insufficient rates of capital investment, difficulties in appropriately developing
local water resources, and the ineffectiveness of institutions mandated to
manage water supplies (in urban areas) or to support community management
(in rural areas).
N Strenuous efforts must be made to improve access to safe and sustainable
water supplies in developing countries, and, given the health burden on the
public and the costs to the health system, health professionals should join with
others in demanding accelerated progress towards global access to safe water.
Water, Diarrhoea, and Infant
Investigations of the costs and health
benefits associated with improvements to
drinking water supply in low-income
countries have concentrated almost
exclusively on how these improvements affect
the incidence of acute infectious diarrhoea
. This focus is not surprising given
that diarrhoeal disease is the second most
common contributor to the disease burden
in developing countries (as measured by
disability-adjusted life years [DALYs]),
and poor-quality drinking water is an
important risk factor for diarrhoea
[18,19]. Most of the excess disease burden
in developing countries falls on young
children17% of all deaths in children
under 5 years are attributed to diarrhoea
. Figures 1 and 2 illustrates how an
inadequate water supply is a contributor to
deaths in children under 5 years [18,19]. It
shows that both the gross domestic
product per capita (GDP)  and the
proportion of the population without
access to improved water are highly
correlated with infant mortality (p,0.001
for both). Both measures remain
indepenBox 1. The Classification of Water-Related Disease
The standard classification of water-related disease was first proposed by David
Bradley  (Table 2). Although there have been suggested improvements since
, none have gained as much recognition as the original system, probably
because they are less focused on disease transmission mechanisms.
Although this four-part classification has served a useful role in highlighting some
of the public health impacts of inadequate water systems, it has also directed
attention away from some other important health issues, namely:
N There is no room in the classification for chemical-mediated diseases such as
arsenic and fluoride poisoning, which have major impacts in certain localities
N The classification takes no account of the impact on health of the need to
collect and transport water for many of the worlds population. For example,
many children and women in developing countries have to carry heavy
containers of water long distances each day, and there have been no systematic
studies about the impact this has on musculoskeletal health.
N The long walks needed to collect water may also increase the spread of certain
infectious diseases though a community. For example, an epidemic of
meningococcal disease in a Sudanese refugee camp seemed to spread along
the routes that people take to collect their water .
N Unpleasant tastes or odours (for example, arising from iron content of
groundwater, or associated with chlorination) in water supplies that are
microbiologically safe may act as a deterrent to use of safe sources, so exposing
users to health risks associated with unprotected water sources.
dent risk factors for infant mortality in a
multiple predictor variable regression.
While this analysis does not prove a direct
causal relationship, since access to
improved water services is likely to be
accompanied by improvements in other
services (such as sanitation), it is clear that
a broad statistical relationship exists
between improved water services and lower
infant mortality for countries of similar
The focus on acute diarrhoea, however,
almost certainly underestimates the disease
burden caused by inadequate water and
sanitation. There is a strong link between
repeat or chronic diarrhoeal disease,
malnutrition, and the poor educational
and physical growth that can seriously
affect the ability of children to reach their
full potential . It has been suggested
that if the impacts of these chronic effects
are taken into consideration, the real
global disease burden due to diarrhoea
(and, consequently, the health benefits of
water and sanitation interventions) would
be about twice the current estimates,
which are based only on acute illness and
The evidence that improving access to
safe drinking water reduces the risk of
diarrhoeal disease in children is strong.
However, since the early 1980s and
especially since Esreys work in the late
1980s , there has been a heated debate
over the relative importance of water
quantity and water quality in reducing
the incidence of diarrhoeal disease. The
rather differing analyses of Esrey and
subsequent workers have led to different
emphases in water supply interventions
especially in regard to the role of
point-ofuse household water treatment
technologies (see Text S1).
Importantly, however, whatever
intervention is introduced, recent evidence
suggests that even occasional short-term
failures in water supply or water treatment
can seriously undermine many of the
public health benefits associated with an
improved water supply . This evidence
is not an argument against attempting to
improve water quality, whether through
community or household water treatment
technologies, but it draws attention to the
vital importance of developing systems
that will continue to deliver safe water in
the long term.
Drinking Water and Nondiarrhoeal
Inadequate access to safe drinking water
is also associated with several
nondiarrhoeal diseases . Chronic or acute
exposure to many organic and inorganic
Box 2. Six Factors That Determine Whether a Water Supply Can Maintain Good Health Effectively
The quality of the water relates to pathogens and chemical constituents in water
that can give rise to both diarrhoeal and nondiarrhoeal disease.
The quantity of water available and used. This is largely determined by (a) the
distance of carry involved, where water has to be transported (often on the heads
or backs of children and women), and (b) the wealth of the user.
Access to water may be primarily a matter of physical distance or climb, but it may
have socioeconomic and/or cultural dimensions if certain social groups are
denied access to particular water sources through cost or culture (see Figure 4).
The reliability of both unimproved and improved water supplies. Many cities in
Asia, for example, supply piped water for only a few hours per day, or for a few
days in every week and many unimproved rural water supplies dry up regularly.
The cost of water to the user. This is represented by the cash tariff that is paid to a
utility or provider or, in the case of unimproved water supplies, by the time and
health penalty paid by the user.
The ease of management for the end user. In urban utility-managed supplies the
user merely pays a tariff; in rural settings in developing countries, users are
expected to play a major part in operation, maintenance, and management.
chemical agents has been implicated in
adverse health effects that range from
acute nausea and vomiting or skin rashes,
to cancer and foetal abnormalities .
Inorganic pollutants in drinking water that
have been linked with disease include
arsenic, copper, fluoride, lead, and nitrate.
Organic compounds that have caused
concern include pesticides, chlordane,
phenol, and trihalomethanes . More
recently, endocrine-disrupting compounds
and pharmaceuticals in drinking water
have been causing concern .
In the developing world, one of the
most dramatic demonstrations of the link
between drinking water and nondiarrhoeal
disease is the arsenic crisis in Bangladesh
. Arsenic in drinking water can have
substantial adverse effects on health,
including skin cancer and gangrene .
The Bangladesh crisis occurred because
boreholes constructed to provide people
with clean drinking water often provided
water with naturally high arsenic
concentrations. Fluoride in drinking water is also
causing increasing concern in the
developing world. About 200 million people are
at risk of exposure to elevated
concentrations of fluoride in drinking water, which
can lead to dental and sometimes skeletal
Figure 1. Global association between national access to improved water source, GDP
and infant mortality. Data sources [6,20,66].
fluorosis [12,28]. Although the global
disease burden estimates for nondiarrhoeal
diseases associated with water supply
problems such as these fall far below
similar estimates for diarrhoeal disease
[29,30], the communities actually affected
by these diseases can suffer severely.
Indirect Links between Water and
In addition to the direct health benefits
of improved safe water supplies, there are
many indirect benefits. For example, the
strong relationship between water and
livelihoods in all regions and economies
of the world affects health indirectly. In
developing countries, deficiencies in water
supply, whether for productive or
domestic uses, have direct negative impacts on
livelihoods; in wealthier countries, past
investment in water infrastructure and the
ability to invest more in the present
increase water security and, arguably,
Lack of water can also lead indirectly to
disease via malnutrition. Several authors
argue strongly for investments in low-cost
water harvesting techniques, irrigation,
and clean water provision as a means of
increasing food production and reducing
infectious disease burden [32,33].
Numerous examples exist across sub-Saharan
Africa and south Asia in which access to
a small amount of irrigated land has
transformed food security for highly
vulnerable households . A study of child
nutrition in otherwise comparable
communities with and without access to
irrigation in central Kenya found clear
evidence that irrigation contributed to
higher energy intakes and reduced chronic
malnutrition in children . However,
mixed conclusions were found in a study
comparing households close to and distant
from two dams in Burkina Faso .
Finally, improvements in water supply
are essential prerequisites for improved
personal and home hygiene and to enable
sanitation facilities to be kept clean.
Consequently, the direct health effect of
improved water supply is likely to be
extended by its indirect effects on
sanitation and hygiene.
A recent study of the economic returns
on investments in water supply and
sanitation indicated that every US$1 spent
on water supply and sanitation services
could lead to an economic return of
between $5 and $46, with the highest
returns in the least-developed areas .
Much of this additional income was from
Figure 2. Association between national access to improved water source, GDP and
infant mortality for Africa. Data sources [6,20,66].
the time saved by having reliable water
close to the household. Other studies also
suggest that investments in water alleviate
poverty [37,38]. The balance of evidence
favours the likelihood that water and
sanitation interventions have economic
benefits beyond those that simply relate
to reduced health care costs. Indeed, it has
been argued that adequate water and
sanitation is an essential prerequisite to
economic development. Thus, poor
countries with access to improved water
experienced average annual growth of
3.7% whereas countries with the same
per capita income but without such access
have an annual growth of only 0.1% .
Status and Trends
Nowadays, many more people have an
improved water supply, as defined by JMP
, than in the late 1970s. However, this
increased coverage has only just matched
global population growth. The absolute
number of people lacking access to an
improved water supply has hovered around
1 billion since the late 1970s [6,40].
Unfortunately, it is probable that the
populations remaining to be adequately
served (for example, in remote rural areas
of low-income countries and in the
periurban slums of the worlds towns and cities)
represent the most intractable problems.
The 1990 (base year for the MDGs) and
2008 (most recent) statistics on urban
water supply show coverage rising from
95% to 96%, while the total urban
population has grown over this period
from 2.3 billion to 3.4 billion. In rural
areas, the coverage estimates are 64% and
78% for 1990 and 2008, respectively,
while the total rural population has grown
from 3.0 billion to 3.4 billion (Table 1).
Overall, 84% of people still not enjoying
an improved water supply live in rural
areas, but it is the urban areas that are
struggling most to keep ahead of
population growth rates, which are commonly
double the national averages.
With 2015 (the MDG target year) fast
approaching, there is a heavy emphasis
internationally on accelerating progress
towards the coverage target. Nevertheless,
this push needs to be tempered with
realism and an emphasis on maintaining
existing water supplies in a functional
state. No-one wishes to see developing
countries littered with defunct water
supply systems as a legacy of the MDGs.
Delivering a Better Water Supply
In wealthy nations, high-quality water is
universally available with large amounts of
money being spent to assure reliable
household supplies. In poorer countries,
improved access to water is generally
delivered through communally managed
public water points in rural areas and
unreliable distribution systems in towns
and cities. Unfortunately, many water
supply interventions in developing
countries do not last . In a recent study of
15 villages in South Africa with supposedly
improved water supplies, three villages
had insufficient water because their wells
had dried up or were incapable of meeting
the demand . Five more villages had
no water on the day of inspectiontwo
because their water pump had broken, two
because there was no money to buy diesel
for the pump, and one because the pump
operator was ill. This example illustrates
some of the challenges associated with
keeping water supply systems working over
the long term. Similarly, a study of water
supplies and arsenic mitigation
technologies in Bangladesh found that only about
64% of the interventions were operational
; other studies suggest that across
subSaharan Africa about one third of hand
pumps are nonfunctioning .
Unfortunately, in low-income countries,
revenues recovered from the users of
improved water supplies are frequently
insufficient to meet the real running costs
of both rural and urban water supplies, so
systems either deteriorate or need to be
heavily subsidized. It is important that user
tariffs are affordable, but that promising
approaches for improving revenue
generation include finding ways to reduce or
spread the costs of establishing house
connections (in the case of urban piped
supplies), developing microfinance
instruments for rural user fees, and encouraging
self-help and small enterprise-driven
approaches. Nevertheless, there needs to be
recognition that the true demand for
improved services (expressed as willingness
to pay) may not yet match the level of
service being promoted through
international targets such as those included in the
There is increasing recognition of the
part that self-help (self-supply) initiatives
and small enterprises can play in delivering
improved and sustainable water services. A
recent review of water, sanitation, and
hygiene for the Bill & Melinda Gates
Foundation identified three broad
approaches to service provision: (a) externally
driven approaches (initiated by agencies
other than the water users, and usually
heavily subsidized); (b) self-supply initiatives
(driven by user demand); and (c)
enterprisedriven approaches, in which local private
entities supply goods and services to
organizations (NGOs), and water users directly .
The last two, which could be combined,
represent very different approaches from
the conventional, externally driven
approach. However, a heavy dependence on
private (mostly shallow groundwater)
sources, which may be poorly constructed
and vulnerable to contamination or failure
during dry periods, has important health
Over the last decade, debates about
private sector participation and public
private partnerships for the improvement
of water supply services have generated
more heat than light. There is little doubt
Use of Improved Drinking-Water Sources (% of Population)
South Eastern Asia
Latin America and the Caribbean
Commonwealth of independent states
now that the private sector is unlikely to
invest significant sums to modernize or
extend water supply systems. However,
this sector has always had an important
role in the supply of goods and services,
and in consultancy, supervision, and
capacity-building. These roles are unlikely
to disappear and we therefore take a
pragmatic attitude to the involvement of
the private sector: local context determines
what arrangements work best .
In recent years, WHO has promoted the
idea of Water Safety Plans (WSPs) . A
WSP is a risk-based approach to public
health achieved through water quality and
catchment management strategies under
the slogan managing drinking water
quality from catchment to consumer.
Although the WSP approach is widely
utilised in urban piped supply systems,
there have been few attempts to implement
the approach in rural settings, where
Constraints and Challenges
Why the Slow Progress?
Slow progress toward full water supply
coverage at a national level  may be
related to national GDP , government
effectiveness , or shortages of water
. We have explored the relationship
between these three variables and coverage
Typhoid, Campylobacter, giardiasis, Cryptosporidium, cholera,
enterohemorrhagic and enterotoxigenic E. coli, norovirus, etc.
Infections that spread in communities that have insufficient water
for personal hygiene
Diseases where the causative organism requires part of its
lifecycle to be spent in water
Trachoma, scabies, Shigella
Vector-borne diseases where the insect vector requires access to water Malaria, onchocerciasis, trypanosomiasis
Table 2. Water-related disease.
by statistically analysing the most recent
available global datasets [6,20,51,52].
Unsurprisingly, given the small amounts
of water needed for domestic use, the
national availability of water resources
was unimportant for water supply
coverage. Its significance more locally is
considered below. However, the proportion of
people with access to safe water was
correlated with GDP (p,0.001) and
government effectiveness (p,0.001). In a
multivariate model, GDP remained the
only significant independent covariate.
Clearly, therefore, a low GDP is a major
challenge facing efforts to improve water
supplies. Below we discuss some of the
other reasons for slow progress.
Government effectiveness in
low-income countries is often poor, and
governments often lack capacity or show
institutional weaknesses . Such weaknesses
range from lack of individual professional
skills, understaffing, poor motivation,
inadequate resources, and poor
organisational management, through to
inappropriate policies handed down to local
government from central authorities. In
addition, corruption has been highlighted
as a major threat to service delivery .
Limited effectiveness of the Ministries
and local government authorities
responsible for water supply can be exacerbated by
insufficient political commitment at the
highest governmental levels and by the
weaknesses of private companies
contracted to carry out construction or system
management. Furthermore, the
professional and technical staff of central government
and local authorities often find their own
high levels of commitment constrained by
the systems within which they work.
Dissociation of the Health and Water
In industrialised countries, much of the
early drive to provide water and sanitation
came from the medical community
[54,55]. These days, the responsibility for
the management of these services usually
rests with engineers and others not
formally part of the public health system.
This dissociation of responsibility for water
services from generic public health has led
to problems. For example, although
benefits are usually accrued by the health
service, the costs of water infrastructure
and maintenance are borne by water
utilities or boards, making expenditure
decisions difficult . Nevertheless, the
public health community in general and
the public health consultant in particular
must be intimately involved in the
provision of water services, playing such
important roles as setting the health-based
targets of WSPs  and designing and
managing surveillance systems for
waterborne disease .
The Walkerton tragedya fatal
waterborne disease epidemic in Ontario, Canada
that occurred in 2000provides a good
example of what can go wrong if public
health oversight is completely removed
from water providers . One of the
underlying problems in this outbreak was
that the plant operators did not understand
the importance and significance of water
quality monitoring, so did not monitor
adequately nor report problems when they
occurred. These lapses led to seven deaths
and an estimated 2,000+ illnesses.
The Availability of Water Resources
Sustainable domestic water supplies
depend on the availability of reliable water
resources that can be easily developed.
Fresh water resources are not spread
evenly across the globe (Figure 3). Most
of the wealthier areas of the world
experience sufficiently frequent rainfall to
replenish rivers, reservoirs, and aquifers
reliably, and have the capacity to store and
transfer that water . Nevertheless,
even wealthy countries are not free from
the problems of occasional droughts, as
recently seen in Spain and Australia.
In many parts of Africa and Asia, the
long dry season and dispersed nature of
many of the populations who currently
have no reliable water supply mean that
the development of groundwater (a
natural reservoir) is the only realistic option for
significantly improving drinking water
coverage . Consequently, statistics on
national water resources are not a good
indicator of water scarcity for much of the
global population. The important factor is
the availability of water resources (usually
groundwater) close to the point of need.
Groundwater is not a panacea, however,
and its development and use need careful
attention. First, in some locations even
small-scale groundwater supplies can be
difficult to find and develop . Such
locations are often a priority for water
supply intervention since they are beset
with diseases related to high dependence
on contaminated surface water sources. A
lack of appreciation of the variability in
the nature and occurrence of water
resources is a major reason for expensive
and unreliable supplies .
Second, groundwater resources rely on
rainfall for renewal and are strongly
affected by climate variability and climate
change . Overabstraction of water,
which can lead to falling water levels and
the exhaustion of resources, is a growing
global problem, exacerbated by climate
change, population growth, and
urbanisation (see Text S2) .
Finally, ground water sources across the
globe are increasingly being polluted
through intensive agriculture, industry,
and poor sanitation . For wealthy
countries, this increases the costs of
providing access to safe water, because
more extensive water treatment is
required. In poor countries, expensive water
treatment is not affordable and there is
little option but to drink increasingly
Management of Water Supply
One of the myths of community water
supply in rural areas of low-income
countries is that users benefiting from
access to modern technology will, after a
short period of training, manage the
system themselves. The reality is that years
of external support may be needed to
build the necessary capacity . Without
ongoing external support (which is often
absent in the context of weak local
government), communities often fail to
effectively manage modern technology for
more than a few years.
Ever since Schumachers seminal work
promoting the idea of intermediate
technology, individuals and organisations
engaged in poverty alleviation have
struggled to define what is now called
appropriate technology . The key is the
match, or fit, between the technology,
the users, and those who have to manage
and maintain it. Whether we are dealing
with a rural water supply system managed
mainly by the user community , or a
more technically sophisticated urban
supply system (see Text S3), this fit is essential.
Modern technologies are only manageable
if the right skills, resources, and incentives
exist, and if appropriate support structures
The level of water sector financing in
low-income countries is widely criticised as
being inadequate, but at the same time
water supply budgets are often
underutilised or ineffectively used. Delays in the
release of central government funds to
local authorities combine with inadequate
allocations for operational expenses to
render local governments ineffective in
disbursing the funds that do reach them.
Importantly, though, the additional
US$11.3 billion that is needed annually
to meet the water and sanitation MDG
targetsa relatively small investment (a
few dollars per capita per year) that is
highly feasible and within the reach of
most nationswould yield an estimated
seven-fold return .
Improved water supplies (in JMP
terminology) usually attract a tariff or water
charge. In low-income countries it is
common for such tariffs to be set at levels
that are below the real running costs. In
such cases a vicious circle often becomes
established, in which below-cost tariffs
lead to inadequate investment in
maintenance, which results in deteriorating
service and further unwillingness to pay
even low tariffs.
Water consumers without an improved
water supply do not pay a financial tariff
for water. Even though they may pay
heavily in terms of health, time, and
energy, it often proves extremely difficult
to change the mindset of consumers who
are used to water being free. Even small
water charges are not welcomed by
consumers, and revenue collections that
start as regular monthly charges often
deteriorate to ad hoc collections or
disappear altogether. Financial
irregularities also often militate against continued
payment of charges.
Strategies to Achieve an Improved
Access to a safe and continuous supply
of water for drinking, cooking, and
personal hygiene is an essential
prerequisite for health. An inadequate water
supplywhether as a result of poor access
or quality, low reliability, high cost, or
difficulty of managementis associated
with significant health risks. These health
risks are experienced most strongly by the
poorest nations, and the poorest
households within nations. A good water supply
is necessary for good sanitation and
hygiene, and to underpin livelihoods,
nutrition, and economic growth.
The global MDG target on water
supply is likely to be met  but will leave
many hundreds of millions of people
without an adequate water supply.
Furthermore, the targets are highly unlikely to
be met in sub-Saharan Africa. Failure to
extend water supply services at an
adequate pace is largely a consequence of high
population growth rates in the low-income
countries, insufficient investment
(although the sums needed are not large),
and poor governance. Failure of existing
water supplies is often due to weak
financial and management arrangements
for operation and maintenance, and a
mismatch between the technology, the
water environment, and the capacity of
users to maintain systems. The result is
poorly performing or broken down urban
and rural water supply systems, and
continuing poor health.
While the health systems of developing
countries are not directly responsible for
changing this situation, poor water
supplies place large burdens of disease on
their populations, and it is those
populations and their national health services that
pick up the costs of diarrhoea and other
diseases. Health professionals should
therefore join those from other sectors
(infrastructure, education, and economic
development) in demanding change.
However, it is clear that many
uncertainties remain about how to improve
public health through improvements in
the water supply. Thus, more and better
research is desperately needed, in
particular larger and longer double-blinded
randomized controlled studies of the
health impacts of water supply and quality
interventions at the community and
But it is equally clear that action must
not wait for the outcomes of such research.
We know enough now about the
importance of improved water supply,
sanitation, and hygiene in relation to health to
consider universal access to these services
to be an urgent imperative.
Text S1 Quantity versus quality and the
role of household water treatment.
Found at: doi:10.1371/journal.pmed.
1000361.s001 (0.09 MB PDF)
Text S2 Climate change, drinking water,
Found at: doi:10.1371/journal.pmed.
1000361.s002 (0.07 MB PDF)
Text S3 The growing issue of urban
Found at: doi:10.1371/journal.pmed.
1000361.s003 (0.07 MB PDF)
ICMJE criteria for authorship read and met:
PRH AMM RCC. Agree with the manuscripts
results and conclusions: PRH AMM RCC.
Analyzed the data: AMM. Wrote the first draft
of the paper: PRH. Contributed to the writing
of the paper: PRH AMM RCC. Participated in
co-author meetings to agree on structure and
content of paper; drafted sections of the paper
under senior authorship of PRH.
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