Chapter 10
Safe Drinking Water: Concepts, Benefits, Principles and
Standards
Safe Drinking Water: Concepts, Benefits, Principles and
Standards
Megersa Olumana Dinka
Megersa Olumana Dinka
Additional information is available at the end of the chapter
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/intechopen.71352
Abstract
Water is connected to every forms of life on earth. As a criteria, an adequate, reliable,
clean, accessible, acceptable and safe drinking water supply has to be available for vari-
ous users. The United Nation (UN) and other countries declared access to safe drinking
water as a fundamental human right, and an essential step towards improving living
standards. Access to water was one of the main goal of Millinium Development Goals
(UN-MDGs) and it is also one of the main goal of the Sustainable Development Goals
(SDGs). The UN-SDG goal 6 states that “Water sustains life, but safe clean drinking water
defines civilization”. Despite these facts, there are inequalities in access to safe drinking
water in the world. In some countries, sufficient freshwater is not available (physical scar-
city); while in other countries, abundant freshwater is available, but it is expensive to
use (economic scarcity). The other challenge is the increasing population of the world at
an alarming rate, while the available freshwater resources almost remains constant. This
chapter presents aspects of safe drinking water - background information, definition of
water safety and access, benefits, principles and regulations, factors challenging the sus-
tainable water supply and water quality standards and parameters.
Keywords: accessibility, inequalities, quality standards, safe water, water uses
1. Introduction
Water covers more than two-thirds of the earth’s surface, but mostly salty and undrinkable.
The available freshwater resource is only 2.7% of the available water on earth but only 1% of
the available freshwater (in lakes, rivers and groundwater) is accessible. Most of the available
freshwater resources are inaccessible because they are in the hidden part of the hydrologic
cycles (deep aquifers) and in glaciers (frozen in the polar ice), which means safe drinkable
water on earth has very small proportion (~3%) in the freshwater resources. Freshwater can
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Safe Drinking Water: Concepts, Benefits, Principles and Standards 173
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In this regard, the water service providers are well aware of the stability of WSS and know
when the system experience a pressure or disruptive influences.
Challenges for water supply and Governance: Cities struggling to keep pace with popula-
tion and demographic changes are not unique. According to a study conducted in Dublin [41],
collectively there are combinations of factors that create an inordinately challenging situation
for those attempting to plan for the city’s current and future water resources needs. Their
main challenges related to topography, old infrastructure (the nineteenth century), popula-
tion growth and development needs, water charges, climate change and water supply history.
5. Drinking water quality
5.1. Definition and concepts
Water is most fundamental in shaping the land and regulating the climate. It is one of the
most important resources that profoundly influence life. Water quality is the most fundamen-
tal controlling factor when it comes to health and the state of diseases in both humans and
animals. According to WHO report [23], about 80% of all the human diseases in human beings
are caused by water.
Depending on the purpose of water quality analysis, water quality can be defined based on a set
of biological, physical and chemical variable, which are closely linked to the water’s intended
use. As a principle, drinking water is supposed to be free from harmful pathogens and toxic
chemicals [3]. Contamination of freshwater (especially groundwater) sources is one of the main
challenges currently faced by the South Africans, more especially in communities who depend
almost exclusively on groundwater [52]. Groundwater is used for domestic, industrial and
agricultural water supply in all four corners of the world. Therefore, the presence of contami-
nants in natural freshwater continues to be one of the most important environmental issues in
many areas of the world, more especially in developing countries [53]. Once the groundwater
is contaminated, its quality cannot be restored back easily, the best way is to protect it.
The concept and theory of water quality is very broad since it is influenced by many factors.
Water quality is based on the intended uses of water for different purposes, that is, differ-
ent water uses require different criteria to be satisfied. In water quality analysis, all of the
accepted and unaccepted values must be clearly defined for each quality variable. If the qual-
ity variables meet the pre-established standards for a given use is considered safe for that use.
When water fails to meet these standards, it must be treated if possible before use.
5.2. Description of water quality parameters
5.2.1. Physical parameters
Physical quality parameters are related to total solids content, which is composed of float-
ing matter, settleable matter, colloidal matter and matter in solution. The following physical
parameters are determined in water [12]:
174 Water Challenges of an Urbanizing World
• Color: caused by dissolved organic materials from decaying vegetation or landfill leachate.
• Taste and odor: can be caused by foreign compounds such as organic compounds, inor-
ganic salts or dissolved gases.
• Temperatures: the most desirable drinking water is consistently cool and does not have
temperature fluctuation of more than a few degrees. Groundwater generally meets these
criteria.
• Turbidity: refers to the presence of suspended solid materials in water such as clay, silt,
organic material, plankton, and so on.
5.2.2. Chemical parameters
The chemical constituents have more health concerns for drinking water than for the physi-
cal constituents. The objectionability of most of the physical parameters are based on esthetic
value than health effects. But the main objectionability of some of the chemical constituents
is based on esthetic as well as concerns for adverse health effects. Some of the chemical con-
stituents have an ability to cause health problems after prolonged period of time [54]. That
means the chemical constituents have a cumulative effect on humans. The chemical quality
parameters of water include alkalinity, biological oxygen demand (BOD), chemical oxygen
demand (COD), dissolved gases, nitrogen compounds, pH, phosphorus and solids (organic).
Sometimes, chemical characteristics are evidenced by their observed reactions such as in laun-
dering, redox reactions, and so on [12, 54].
Below is a list of some of the chemical compounds and elements found in water:
• Arsenic: occurs naturally in some geologic formation. It is mostly used in agricultural
chemicals in South Africa. In drinking water, it has been linked to lung and urinary blad-
der cancer.
• Chloride: most waters contain some chloride. The amount found can be caused by the
leaching of industrial or domestic waters. Chloride should not exceed 100 mg/L in domes-
tic water to be palatable.
• Fluoride: is a natural contaminant of water. It is one of those chemicals given high
priority by WHO [14] for their health effects on humans. High F in drinking water usu-
ally causes dental and skeletal fluorosis. Excessive F (>2 mg/L) causes a dental disease
known as fluorosis (mottling of teeth), while regular consumption in excess may give
rise to bone and skeletal fluorosis [12]. On the other hand, F < 2 mg/L causes dental
cavities in children.
• Zinc: is found in some natural waters, particularly in areas where zinc ore deposit have
been mined. Though it is not considered detrimental to health, but it will impart a bad taste
to drinking water.
• Iron: small amounts of iron frequently are present in water because of the large amount of
iron in the geologic materials. This will cause reddish color to water.
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• Manganese: naturally occurring manganese is often present in significant amounts in
groundwater. Anthropogenic sources include discarded batteries, steel alloy production
and agricultural products.
• Toxic substances: generally classified as inorganic substances, organic substances and
heavy metals. The toxic inorganic substances include nitrates (NO3), cyanides (CN_) and
heavy metals. These substances are of major health concern in drinking water. High NO3
content can cause Methemoglobinemia in infants (“infant cyanosis” or “blue baby syn-
drome”); while CN can cause oxygen deprivation [12]. There are more than 120 toxic or-
ganic substances [24], generally exist in the form of pesticides, insecticides and solvents.
These compounds produce health effects (acute or chronic). The toxic heavy metals are ar-
senic (As), barium (Ba), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), selenium
(Se) and silver (Ag) [12]. Like the organic substances, some of these substances are acute
poisons (As and Cr) and others produce chronic diseases (Pb, Cd and Hg).
5.2.3. Biological parameters
Biological parameters are the basic quality parameters for the control of diseases caused
by pathogenic organisms, which have human origin. Pathogenic organisms found in sur-
face water include bacteria, fungi, algae, protozoa, plants and animals and viruses. Some of
these disease-causing organisms (bacteria, fungi, algae, protozoa and viruses) are not identifi-
able and can only be observed microscopically. Microbiological agents are very important in
their relation to public health and may also be significant in the modification of physical and
chemical characteristics of water [12]. Water for drinking and cooking purposes must be free
from pathogens. The greatest microbial risks are associated with consumption of water that
is contaminated with human or animal feces. Feces can carry pathogenic bacteria, protozoa,
helminthes and virus. Pathogens originating from feces are the principle concerns in setting
health-based targets for microbial safety. Water-borne diseases are particularly to be avoided
because of the capacity of result in the simultaneous infection of large number of people.
While water can be a very significant source of infectious organisms, many of the diseases
that may be waterborne may also be transmitted by other routes, including person-to-person
contact, droplets and aerosols and food intake [54].
The techniques for comprehensive bacteriological test are complex and time consuming.
Different tests have been developed to detect the relative degree of bacterial contaminations
in terms of an easily defined quantity. There are two mostly used test methods widely used
to estimate the number of microorganism of coliform groups (Escherichia coli and Aerobacter
aerogenes). These include: total coliforms or E. coli, but the second one is found to be a better
indicator of biological contamination compared to the first one [12].
5.3. Water quality standards
As presented in Section 3.1, standard is defined as a basis for judging the quality. A standard
for drinking water quality is thus the reference that will ensure that the delivered water will
not pose any threat or harm to human health. The water quality standard is the framework
