At the dawning of a new
millennium, at least one-fifth of all people worldwide lack access
to safe drinking water, according to a 1999 United Nations (UN)
comprehensive assessment of world water resources, and more than
one-half of all people lack access to adequate sanitation. These
problems will almost certainly get much worse as the earth's
population grows from today's 6 billion to an expected 7.3-8.3
billion people by 2025, according to the UN Population Division.
During the last century in particular, steps have been taken to
develop the technology and social policy to address questions of
access to potable water, adequate sanitation, and means of improving
water quality. Improvements have been made, mainly in developed
countries. However, problems continue even there, and the situation
in developing countries is far worse.
In developed countries, including the United States, western
European nations, and Japan, some drinking water supplies contain
synthetic organic chemicals, lead, arsenic, and fecal wastes that
carry dangerous bacteria, viruses, and parasites, potentially posing
increased risks of cancer, infections, and birth defects. Polluted
water can cause a variety of gastrointestinal illnesses, including
dehydration from severe diarrhea or vomiting that can be fatal in
children, the elderly, and people with weakened immune systems.
Industries discharge wastes into rivers and streams or dispose of
them in landfills, lagoons, and dumps, where the pollution can leak
into shallow water tables connected to lakes and streams, and
eventually into aquifers. In the United States, for example,
fertilizers and pesticides spread on farms and lawns filter through
the ground into the water table or wash into streams and lakes,
which supply half of the nation's drinking water.
Most cities in developing countries discharge 80-90% of their
untreated sewage directly into rivers and streams, which are used
for drinking, bathing, and washing, according to Sandra Postel,
director of the Global Water Policy Project, a research program on
sustainable water use. For example, of India's 3,119 larger cities,
only 209 have partial wastewater treatment plants. Just 8 have full
treatment facilities.
In recent years, this lack of sewage treatment has allowed
dangerous microorganisms to spread, as in South America, where the
cholera bacterium threatens drinking water and food supplies. Today,
impoverished people in developing countries still face catastrophic
losses of life due to dirty water. Human feces remains one of the
world's most dangerous pollutants, spreading microbes that cause
typhoid, cholera, diarrheal illnesses, amoebic dysentery, and other
virulent diseases. Diseases caused by tainted drinking water and
food claim nearly two million lives a year among children under the
age of five worldwide, according to a 1999 report by the World
Health Organization (WHO) titled Removing Obstacles to Healthy
Development.
Starting in Soho
In 1854, the Soho neighborhood of London was rocked by a cholera
epidemic. Physician John Snow, who suspected that contaminated water
was causing the outbreak, drew a map indicating the location of
every cholera case in Soho. From this map, Snow could see that the
highest concentration of illness occurred in homes that used the
public water pump on Broad Street. After he recommended that
authorities remove the pump, the number of new cholera cases in Soho
plummeted. Snow's brainstorm was just one part of a revolution in
public health in the 1840s and 1850s, when London, Paris, and other
European cities began to battle waterborne infectious diseases by
improving sewer systems. Largely as a result of this revolution,
life expectancy rose dramatically over the next half-century.
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Micromenace. In developed and
developing countries alike, microbial contaminants such as
Salmonella plague drinking water supplies.
Photo credit: Partnership for Food Safety
Education |
After the turn of the 20th century, improvements in water
supplies picked up momentum throughout the industrializing world. In
1908, Jersey City, New Jersey, became the first municipality in the
United States to treat drinking water with chlorine to reduce health
risks from dangerous microorganisms. Nevertheless, in the 1920s and
1930s there were a number of outbreaks of typhoid fever and amoebic
dysentery in the United States after people drank contaminated
water. By 1945, to prevent such outbreaks, large water systems were
using disinfectants (especially chlorine) and improved filtration,
while communities provided better disposal of wastewater.
Even today, though, sewage treatment is not aimed at controlling
specific microbial contaminants, and microbial pollution has again
emerged as a serious problem in the United States and other
developed countries. Microbial pathogens in U.S. public water
supplies sicken hundreds of thousands of people each year, and
though most of these illnesses are mild, disappearing after a few
days, chronic outcomes such as myocarditis resulting from these
infections are of significant concern. Only in some states do
drinking water suppliers monitor and treat for certain dangerous
viruses and parasites.
Meanwhile, thousands of public water systems annually violate one
or more federal drinking water regulations. In the great majority of
cases, small systems, which serve fewer than 3,300 people, are the
chronic violators. One problem is that small systems must comply
with standards for treatment and monitoring that were developed as
affordable for large systems. Because small systems do not have
economies of scale to cope with the growing costs of new rules, even
the most efficient small suppliers struggle to keep up.
But in larger water systems, major accidents still happen. In
late March and early April of 1993, a surge of the parasite
Cryptosporidium slipped through the water treatment filters
in Milwaukee, Wisconsin. An estimated 400,000 people became sick
from drinking the contaminated water, suffering from diarrhea,
abdominal cramping, nausea, vomiting, and fever. At least 50 people
with compromised immune systems died in the wake of the outbreak.
Cryptosporidium is an especially difficult organism to
control because traditional disinfectants such as chlorine don't
kill it, and the organism must be filtered out.
Fifteen years ago, the U.S. Environmental Protection Agency (EPA)
and Congress primarily focused their attention on toxic chemicals in
drinking water. In 1986, when the Safe Drinking Water Act was first
reauthorized, Congress sought to limit certain chemicals in drinking
water to address a possible cancer risk. Congress instructed the EPA
to establish standards for 83 contaminants within three years and
for 25 new chemical contaminants every three years after that.
In 1996, when the Safe Drinking Water Act was again reauthorized,
the requirement for new chemical standards was drastically scaled
back, and Congress and the EPA set a new health priority for
Cryptosporidium and other dangerous waterborne microbes.
Nevertheless, health officials were still concerned about
by-products of chlorine and other disinfectants that may cause some
forms of cancer. In 1996, the EPA promulgated an Information
Collection Rule requiring water systems that serve more than 100,000
people to collect and report information on the presence and
concentrations of microbial contaminants and disinfection
by-products.
In December 1998, the EPA proposed the Interim Enhanced Surface
Water Treatment Rule, which would require improvements in filtration
at water systems that serve at least 10,000 people. In addition,
states would be required to conduct sanitary surveys of all water
systems, including those that serve fewer than 10,000 people.
Experts say the United States probably has some of the cleanest
drinking water in the world. The vast majority of industrial
discharges into waterways are regulated and treated to some degree.
After massive public investments under the Clean Water Act over the
past two decades, cities and towns have upgraded their treatment of
sewage. And drinking water suppliers monitor and treat for chemical
contaminants and microorganisms to protect public health.
A Developing Problem
Developing countries have not been as successful in implementing
such monitoring and treatment programs. Joan B. Rose, a
microbiologist at the University of South Florida in St. Petersburg
who has organized workshops in Brazil, Mexico, Argentina, and Panama
on water monitoring and risk assessment, notes that South American
nations generally don't have sewage treatment. These nations have
far greater problems with drinking water contamination than does the
United States.
In the early 1990s, an epidemic of cholera sickened 350,000
people throughout the continent, killing more than 3,600. Cholera
was able to spread rapidly through South America once it took hold
in the early 1990s largely because the bacterium moved from
wastewater systems to drinking water supplies, Rose says.
Today, 17 cities in the developing world are considered
megacities, with more than 10 million people. This explosive growth
of densely populated cities with unsafe water, poor sanitation, and
widespread poverty has established an ideal breeding ground for
infectious diseases, according to the WHO. It is difficult and
expensive to supply clean water and adequate sanitation to 10-20
million people living in a concentrated area, as it requires
enormous investments in sewer construction, treatment plants, and
personnel.
Even so, large cities in developing countries receive the
overwhelming majority of public funds spent on improved water
supplies and sanitation. "Governments and businesses in developing
countries are located in the urban areas," says Ted Kuepper, project
manager for Global Water, an international nonprofit organization
that has helped establish deep wells for drinking water in countries
such as Kenya, Laos, and Peru. "The political power is in the
cities, and leaders don't expect to get anything back politically
from rural areas, which have been incredibly neglected over the
years [in terms of investments in clean water]," he says.
In many poor villages, people have to rely on the water that's
easiest to reach through shallow groundwater wells, usually less
than 10 feet deep, or mud holes used by both animals and humans.
Even when there is a stream or river nearby, these water sources are
frequently polluted with animal and human waste.
Especially for mothers in poor communities, the convenience and
quantity of water are crucial, according to Sandy Cairncross, head
of the Disease Control & Vector Biology Unit at the London
School of Hygiene & Tropical Medicine. Women with small children
particularly need a nearby source of water to maintain domestic
hygiene, because numerous infectious diseases are spread primarily
by contact with human waste. Microorganisms that cause cholera,
severe diarrhea, and other illnesses are often present in huge
numbers in infected human feces, and if someone drinks water
containing these dangerous microbes, the illness can be quickly
passed on. Diarrheal infections travel not only through water
supplies but also via contaminated food, utensils, and fingers.
Cairncross notes that in Bangladesh, poor women sometimes use a
section of their saris to wipe dishes, clean children's faces, and
wipe children's bottoms. Thus, a local water supply can be
relatively clean, yet diseases still spread. And they still kill.
Parents are often shocked at how quickly severe dehydration can
kill young children. Yet diarrheal afflictions can be readily
treated with an oral rehydration solution. Indeed, over the past
decade Mexico has significantly reduced death rates from waterborne
infectious diseases by distributing this medicine to health centers
and improving health education, according to the WHO report.
Still, it's very difficult to control diarrheal diseases without
readily available water to maintain hygiene. For many poor people,
the only source of water is a long hike from home. "If the water
supply is a mile away, women and children are spending a good part
of their day just walking back and forth getting it," says Kuepper.
But when people have taps near their homes, their water use rises
dramatically, and "most of the increase in water consumption is for
hygiene purposes," says Cairncross. Studies show, he says, that
hygiene does improve when people have on-plot or in-house water
supplies. But this can be economically impractical. "Piped-in water
for every home is very expensive," says Postel. The challenge for
many poor regions is to find methods of supplying low-cost,
convenient, clean water to neighborhoods and communities, without
necessarily providing piped-in supplies to individual homes.
A Scarce Resource
In the coming decades, there will be increasing competition for
water supplies worldwide. North Africa and the Middle East are the
global regions most challenged by water scarcity today. But
sub-Saharan Africa, including countries such as Rwanda and Kenya,
will also be affected as the region's population doubles or even
triples in size over the next 50 years, predict Robert Engelman and
Tom Gardner-Outlaw, coauthors of the 1997 report Sustaining
Water, Easing Scarcity: A Second Update, published by Population
Action International, a nonprofit organization based in Washington,
DC. The researchers examined how much renewable fresh water is now
available in each country, and by using various UN projections on
population growth, estimated how much water will be available in the
future. According to the report, by the year 2050 at least one in
four of the world's people is projected to live in a country with a
chronic shortage of fresh water. Still, the report refers to water
scarcity in terms of economic development and agricultural
needs--not in terms of drinking water.
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A precious commodity. The need
for clean water for hygiene is particularly pressing for women
and children in poor communities, who may be most susceptible
to the transmission of infectious
diseases. |
In general, few countries maintain significant data on drinking
water as a particular category, with the exception of the United
States and certain other developed nations. "For most developing
countries, drinking water is not a special category," says Engelman,
who is also director of the Population and Environment Program at
Population Action International. "Drinking water is a very small
minority of water use."
Even so, experts agree that rapidly growing cities, with rising
populations and water-hungry industries, will increasingly compete
for supplies now used by agriculture. Today, irrigation consumes
about 70% of available fresh water worldwide. But there is only so
much water to go around in water-scarce regions, says Postel. In
several international river basins, rivers are shared by a number of
countries, and populations in those countries are increasing at a
fairly significant rate. That's causing all kinds of demands for
water--for irrigation to grow food, for developing industry for
jobs, and for household use. In the Nile Basin, for example,
Ethiopia, Sudan, and Egypt are competing for irrigation water, and
this competition is expected to grow more heated as the number of
people there increases rapidly over the next 30 years. Still,
providing drinking water is a priority for most governments, and
where water is scarce governments are shifting supplies from
agriculture to industry and to cities for household use. This
phenomenon is occurring in parts of India, China, Southeast Asia,
and even the United States.
Some of the world's most serious water shortages are caused by
government policies that encourage waste. In many developing
countries, water is heavily subsidized, priced far lower than the
cost of storing, transporting, and treating it, and with such low
prices, there is little incentive to conserve water. Water subsidies
are provided primarily to prosperous city dwellers with access to
public systems and to rural farmers who can take irrigation water
essentially for free.
In the vast shantytowns surrounding the megacities of the
developing world, municipal services, including water and sewage,
are not available. So the poor have to rely on vendors, who show up
in neighborhoods about twice a week with water that may have been
taken from highly polluted sources. Yet poor citizens end up paying
a large portion of their income for this water. Slum dwellers pay
about 12 times more per unit for this "street water" than the prices
that middle-class residents pay for piped-in municipal supplies,
according to a 16-city review of water vending presented in August
1999 at the Second Meeting of the World Commission on Water for the
21st Century, which is supported by agencies of the UN and the World
Bank. The review reported the example of Lima, Peru, where a poor
family typically pays street vendors $3 per cubic meter of water,
more than 20 times what a middle-class family pays for water through
a piped-in house connection.
Some of the largest cities, such as Mexico City, depend on
diminishing supplies of groundwater, which is often the cleanest
source of water. Underground aquifers begin 30-100 feet beneath the
land surface. Because water gravitates very slowly from the earth's
surface to an aquifer--a fraction of an inch to a few feet per
day--it usually takes many years for an aquifer to be refilled. When
enormous amounts of water are drawn out too quickly with powerful
pumps, aquifers can be depleted. As water quantity shrinks, water
quality can be affected, because declining supplies lose their
capacity to dilute pollutants and salinity. For example, in
Bangladesh and West Bengal, India, receding water tables have
exposed arsenic-laden sediments to oxygen, apparently converting
them to a water-soluble form. Tens of millions of people in West
Bengal are drinking groundwater with arsenic concentrations well
above acceptable levels. Thousands have been diagnosed with symptoms
of arsenic poisoning such as skin lesions, according to the April
1999 Source Bulletin, published by the International Water
and Sanitation Centre and the Water Supply and Sanitation
Collaborative Council, agencies of the WHO.
Climate Change
Yet another factor affecting the availability of clean water is
climate change, which has been credited as the cause of outbreaks of
waterborne illnesses around the world. Global warming is
intensifying the hydrological cycle, drawing more moisture into the
atmosphere and altering patterns of precipitation. "A moisture-laden
atmosphere . . . generates more tropical-like downpours that . . .
flush nutrients, chemicals, and microorganisms into waterways,"
wrote Paul R. Epstein, associate director of the Center for Health
and the Global Environment at Harvard Medical School in Boston,
Massachusetts, in a 16 July 1999 article in Science. Massive
flooding often contaminates wells and water treatment facilities,
allowing the spread of the cholera bacterium and other pathogens.
For instance, during the 1997-1998 El Niņo event, the Horn of
Africa was struck by heavy rains--up to 40 times the average
rainfall--causing tens of thousands of cases of cholera. Hurricane
Mitch, which was strengthened by the warm waters of the Caribbean,
battered Central America in November 1998, spawning more than 30,000
cases of cholera. And many microorganisms are thriving in the new
climate conditions. "With warming, we're seeing more growth of
organisms [that cause disease]," says Epstein. "Warm temperatures
can increase the rate of growth of microorganisms such as
Salmonella." Indeed, a recent study by researchers at the
University of South Florida and The Johns Hopkins University in
Baltimore, Maryland, has shown that in the last 20 years 20-40% of
drinking water-related outbreaks in the United States have occurred
during extreme precipitation events. The researchers mapped the
outbreaks from 1970 to 1994 and then compared precipitation data
during the outbreaks to average rainfall for that time of year. Says
Rose, "The results have suggested that rainfall is a significant
contributor to the contamination that overwhelms many water
systems."
Meanwhile, some dry regions are experiencing more severe droughts
as their climates change. In drought conditions, people lack enough
water to stay clean, and disease can spread rapidly. Moreover, in
some arid regions, a lack of water has been creating environmental
refugees in recent years. Driven from their homes to look for food
and water, these refugees eventually settle in overcrowded temporary
villages, where they are vulnerable to epidemics of dysentery. "The
main reason that people have to move from their homes is because of
a lack of water," says Kuepper.
Where the Water Is
In most regions of the world, water is not so much scarce as it
is badly distributed, says Postel. "There is enough to provide
everyone with drinking water, but governments, international
agencies, and the private sector have not been mobilized to provide
that water."
Kuepper agrees that impoverished rural areas could gain access to
water at minimal cost. In many places, he says, "there are stable
and consistent groundwater supplies, where aquifers are just so
large. These are places that experience scarcity, yet local people
lack the technologies to gain access to groundwater." Global Water
projects help nongovernmental agencies in developing countries build
low-cost, small wells less than 100 feet deep that can pump 10-15
gallons a minute with hand pumps. When entire villages are supplied
with these wells, solar-powered water pumps are provided as well.
Getting funding for such projects, however, is always a struggle,
Kuepper says.
The UN Environment Programme (UNEP) is proposing major
international investments in water and sewage distribution systems.
The agency notes that water could be provided in rural areas through
low-cost technologies similar to those provided by Global Water,
including hand pumps and rainwater collection. These tools would
help bring water to entire rural villages. In cities, UNEP
recommends building better water systems with more pipes, pumps,
worker training, and development and strengthening of management
policies. In total, low-cost safe water could be brought to people
who need it for $23-25 billion per year over 8-10 years, according
to UNEP.
Now international agencies want to bring many of the basic health
advances established in industrialized nations over the past 150
years to the rest of the world. "The health benefits provided by
better water and sanitation are huge," notes John Briscoe, senior
water advisor at the World Bank. "When services were improved in
industrial countries in the 19th and 20th centuries, the impact on
health was revolutionary." Experts suggest that such a revolution is
just what the 21st century needs as well.
John Tibbetts
The Other Side of the Coin: Too Much Water
The 1999 hurricane season was a brutal one for eastern North
Carolina, an area of 18,000 square miles and 2.1 million people. The
region was deluged by three giant storms and more than three feet of
rain in less than two months. First, Hurricane Dennis battered North
Carolina for six days in late August and early September, dumping 8
inches of rain. Just two weeks later, on September 16, Hurricane
Floyd poured up to 20 inches onto the eastern part of the state.
Finally, on October 18, Hurricane Irene brought a third round of
torrential rains, dumping up to 11 inches on some parts of North
Carolina.
The environmental damage from the storms was widespread.
Throughout eastern North Carolina, the unusually high amount of rain
dropped by the storms caused massive flooding, knocking out
electricity in at least 24 municipal sewage treatment plants and
causing spills of raw sewage into coastal rivers, especially
affecting the Tar, Neuse, and Cape Fear. According to Susan
Massengale, spokesperson for the North Carolina Division of Water
Quality, the storm caused five farm-waste lagoons to breach and
hundreds of waste lagoons were filled to high levels with rainwater
so that farmers had to pump huge volumes of diluted animal waste
onto already-saturated sprayfields to keep lagoon dams from breaking
or overtopping. "It could be that the largest source of contaminants
was from pumping to maintain safety of the lagoons," says Joe Rudek,
a senior scientist with the Environmental Defense Fund.
Sea of waste. A nutrient- and sediment-laden
discharge plume (right) inundates Pamlico Sound off the coast of
North Carolina as a result of floodwater discharge from recent
hurricanes.
Photo credit: Hans Paerl
The stormwater from the three hurricanes mixed with raw sewage,
junkyard waste, propane tanks, underground gasoline tanks, runaway
oil drums, and sediments from farm fields. Stormwater included
"anything you could imagine that could be uprooted or inundated or
released during the flooding event," pouring down rivers into
Pamlico Sound, the nation's second-largest estuary, says Hans Paerl,
a marine scientist at the University of North Carolina at Chapel
Hill.
The floodwaters polluted wells, broke water mains, and threatened
water supplies with bacteria, viruses, and parasites, which can
cause a variety of diarrheal illnesses. After Floyd, National Guard
trucks and helicopters were needed to deliver clean water to several
counties in eastern North Carolina.
Yet in the first two weeks after Floyd, state surveyors found
only a slight increase in reported gastrointestinal illnesses and no
outbreaks, says Debbie Crane, a spokesperson for the North Carolina
Department of Health and Human Services. Health officials who
surveyed emergency rooms and some doctors' offices suspect that
stress may have been the contributing factor for the increase in
reported cases, says Crane. By the third week after the storm, no
further increase in reported cases was seen.
But surveys don't tell the whole story. "Most people don't go to
the doctor when they get sick [with gastrointestinal ailments] after
a flood," says Joan B. Rose, a microbiologist at the University of
South Florida in St. Petersburg who studies pathways and
concentrations of pathogenic microorganisms in stormwater runoff.
"They're trying to clean up their house, contact their insurance
company. In emergency rooms, you're more likely to see young
children and infants taken in, not adults."
Meanwhile, the post-Floyd flooding was washing a huge pulse of
freshwater into Pamlico Sound. Because freshwater is less dense than
saltwater and floats on top, it created an "oil-and-vinegar effect,"
says Paerl. The freshwater on top also sealed off oxygen from the
deeper brackish waters of the sound. As a result, two weeks after
Floyd, Paerl found extremely low oxygen concentrations in the bottom
waters of Pamlico Sound--1 milligram per liter compared with the
normal 7 milligrams. The conditions in Pamlico Sound were
reminiscent of conditions in the Gulf of Mexico after its "dead
zone" doubled in 1993, due, some scientists believe, to fertilizer
runoff after massive Midwestern floods that year.
Hurricane Irene, though, brought a surprising development. That
storm stirred up the water column, recirculating fresh- and
saltwater, "flipping the sound over," says Paerl. The combination of
storms has caused a large-scale freshening of Pamlico Sound,
decreasing its surface water salinity from about 20 parts per
thousand to about 6 or 7 parts per thousand and changing the habitat
of the sound for saltwater species.
But it could be next spring or summer, Paerl notes, before
scientists can determine the longer-term effects of the 1999
hurricanes. Over the winter, scientists expect to see continuing
freshwater flows from these storms and large loads of nutrients and
organic matter pouring into the sound. When North Carolina waters
heat up again during spring and summer, says Paerl, there is a
greater likelihood of algal blooms. Nutrients and warm temperatures
stimulate algal blooms, which subsequently decompose, potentially
robbing the bottom water of oxygen.
Most of the nutrients, freshwater, and pollutants flowing into
Pamlico Sound will likely remain there through the summer. The
sound, blocked off by the Outer Banks, has only three very narrow
outlets to the Atlantic Ocean. "It's a very large body of water that
doesn't exchange very readily [with the Atlantic]," says Paerl. "A
drop of water stays in that system for about a year."
John Tibbetts
Last Updated: February 1,
2000