UNIVERSITY OF NAIROBI
DEPARTMENT OF CIVIL ENGINEERING
GROUND WATER AND SURFACE WATER QUALITY
COMPARISON IN LOWER KABETE( KIAMBU COUNTY)
By: MWAURA KENNEDY GATHIRWA
F16/36264/2010
A project report submitted as a partial fulfillment of the requirement for the
award of the degree of Bachelor of Science in Civil Engineering
2015
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DECLARATION
I Mwaura Kennedy Gathirwa, declare that this report is my original work and has not been
presented for a degree in any other University.
Sign………………………………….. Date……………………………………………….. ..
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DEDICATION
This project is dedicated to my beloved parents Mr &Mrs Mwaura for their moral and financial
support. Thank you for believing in me, showing me the value of education and constantly
advising me on life, I would not have come this far without you. May the Almighty bless you.
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ACKNOWLEDGEMENT
I would like to start by thanking the Almighty God for giving me the wisdom, knowledge and
favour while writing this project.
I would like to express my deep gratitude to Dr. P.K Ndiba, my research supervisor, for his
patient guidance, enthusiastic encouragement and useful critiques of this research work. I am
grateful to the Public Health Laboratory Staff (Kaunda, Joy and Wambui) for their devoted help
and cooperation while undertaking the laboratory experiments by availing all the apparatus I
needed and for the limitless advice offered by the them.
THANK YOU.
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ABSTRACT
The purpose of this study was to compare ground water quality and surface water quality as
alternative sources of water to supplement the unreliable piped tap water supply in lower kabete
area, a largely residential area in kiambu county. This study was accomplished by identifying
two streams regularly used by the residents and two boreholes from which samples were taken
and tested for quality of water and assessing the better alternative source of water.
The quality of water is established on a defined basis, usually in terms of quality requirements
for potable water. The water samples were tested for typical parameters such as; chemical
substances, physical properties, toxic compounds and bacterial quality. The values obtained were
compared with the World Health Organization (WHO) drinking water standards.
Rigorous laboratory testing was carried out and for parameters and found to lie within the
following ranges; Total hardness 68 - 304mgCaCO3/l; Turbidity 0.6 – 7.5 FTU; Total alkalinity
41 - 119mgCaC03/l; Iron 0.2 – 0.8 mg/l; Total dissolved solids 112 - 270 mg/l; chlorides 81 248mg/l, pH 6.5 – 7.37; colour 5 - 15 Hazens; Fecal coliform count 28 – 91 and Dissolved
Oxygen 4.79 – 5.82mg/l; fluorides 0 – 1.1mg/l ;Nitrates 2 – 9mg/l. in the above experiments
conducted, Iron was found to be in excess of recommended Drinking Water Quality Standards
for Kenya (1996) in one sample and turbidity was in excess in 2 samples.
It is recommended that, in order to avoid contamination of ground water and streams, there
should be safe and effective handling of both industrial and domestic liquid and solid wastes.
The Kiambu county ministry of water together with water service providers should work on
improving reliability of piped, treated, safe water for the people of lower kabete. Chemical
analysis should be carried out on both water sources more frequently at intervals of maybe 4
months (thrice a year) to ensure that the water consumed is kept on check against the set
standards by WHO and KEBS. Sensitizing the residents on water handling techniques that
minimize contamination such as boiling drinking water and use of disinfectants at point of use
was highly recommended
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1 Table of Contents
4
2)
INTRODUCTION ................................................................................................................................ 2
1.1
Background ................................................................................................................................... 2
1.2
PROBLEM STATEMENT ........................................................................................................... 3
1.3
Objectives of the study.................................................................................................................. 4
LITERATURE REVIEW ..................................................................................................................... 4
2.1
GROUND WATER ...................................................................................................................... 5
2.1.1
Natural contaminants ............................................................................................................ 5
2.1.2
Contaminants due to Human activities and pollution ........................................................... 5
2.2
SURFACE WATER ..................................................................................................................... 8
2.2.1
2.3
3)
4)
POTENTIAL SURFACE WATER POLLUTANTS ............................................................ 8
WATER QUALITY PARAMETERS ........................................................................................ 12
2.3.1
Physical parameters............................................................................................................. 12
2.3.2
Chemical parameters ........................................................................................................... 16
2.3.3
MICROBIOLOGY AND BACTERIOLOGICAL ASPECTS ........................................... 21
CHAPTER 3: METHODOLOGY AND APPROACH. ..................................................................... 24
3.1
INTRODUCTION ...................................................................................................................... 24
3.2
Sampling ..................................................................................................................................... 24
3.2.1
Guidelines for sampling point selection.............................................................................. 24
3.2.2
Sampling process ................................................................................................................ 25
3.2.3
Laboratory tests ................................................................................................................... 25
RESULT ANALYSIS ......................................................................................................................... 26
4.1
Tabulated lab results ................................................................................................................... 26
4.1.1
4.2
Table 4.1.1: lab results table .............................................................................................. 26
Graphical representation and discussion of results ..................................................................... 28
4.2.1
Dissolved oxygen ................................................................................................................ 28
Chart 1:Dissolved oxygen chart .......................................................................................................... 28
4.2.2
Hardness...................................................................................................................................... 29
Chart 2: Hardness chart ....................................................................................................................... 29
4.2.3
Alkalinity ................................................................................................................................ 30
Chart 3: Alkalinity chart ..................................................................................................................... 30
4.2.4
solids ........................................................................................................................................... 31
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4.2.5
Iron ...................................................................................................................................... 32
Chart 5: Iron chart ............................................................................................................................... 32
Chlorides ..................................................................................................................................... 33
4.2.6
Chart 6: Chlorides chart ...................................................................................................................... 33
colour .......................................................................................................................................... 34
4.2.7
Chart 7: Colour chart .......................................................................................................................... 34
4.2.8
Turbidity ............................................................................................................................. 35
Chart 8:Turbidity chart........................................................................................................................ 35
Fluorides ............................................................................................................................. 36
4.2.9
Chart 9: Fluorides chart....................................................................................................................... 36
4.2.10
Nitrates ................................................................................................................................ 37
chart 10: Nitrates chart ........................................................................................................................ 37
4.2.11
pH........................................................................................................................................ 38
Chart11: pH chart ............................................................................................................................... 38
4.2.12
plate count .......................................................................................................................... 39
Chart 12: plate count chart .................................................................................................................. 39
4.3
5.1
Comparison of results ................................................................................................................. 40
conclusion ....................................................................................................................................... 42
List of illustrations
List of illustrations
page
Illustration 1: Ground water contamination.......................……….......................……….......... 5
Illustration 2: pH ranges.............................................................................................................. 12
List of Tables
page
Table 01: Various sources of odour in water................................................................................9
Table 02: Various sources of taste in water.....……............... ..................……………………....10
Table 03: Hardness table...............................................................................................................13
Table 4.1.1: Lab results table.........................................................................................................19
Table 4.3.1: Results comparison table ..........................................................................................28
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List of Charts
page
Chart 1:Dissolved oxygen chart.....................................................................................................37
Chart 2: Hardness chart.................................................................................................................38
Chart 3: Alkalinity chart................................................................................................................39
Chart 4: Solids chart.......................................................................................................................40
Chart 5: Iron chart..........................................................................................................................41
Chart 6: Chlorides chart.................................................................................................................42
Chart 7: Colour chart.....................................................................................................................44
Chart 8: Turbidity chart.................................................................................................................45
Chart 9: Fluorides chart.................................................................................................................46
chart 10:Nitrates chart....................................................................................................................47
chart 11: PH chart..........................................................................................................................48
chart 12: plate count chart..............................................................................................................49
CHAPTER 1 :
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4
INTRODUCTION
1.1 Background
All over the world, governments are striving to ensure that their citizen have access to sufficient,
reliable and safe drinking water at an affordable price. However this has not been achieved
especially in the sub-Saharan Africa. Kenya has for long been considered a country with
insufficient water supply. Approximately 17 million Kenyans lack access to clean water
(www.nytimes.com, 2013),
Public health refers to the science and art of preventing disease, prolonging life and
promoting health through organized efforts and informed choices of society, organizations,
public and private, communities and individuals ( wikipedia.org/wiki/Public health).It is our role
as public health engineers to do the above by providing sanitation facilities, community
sensitization, testing alternatives and ensuring that water supplied to people conforms to the set
national and international standards
Water quality refers to the chemical, physical, biological, and radiological characteristics
of water. It is a measure of the condition of water relative to the requirements of one or more
biotic species and or to any human need or purpose. There are numerous regulatory bodies that
standardize the quality of water before it reaches the consumers. They include:-
i.
Water Services Regulatory Board (WASREB),
ii.
Water and Sanitation Program (WSP),
Other independent monitoring bodies are:-
i.
Ministry of Water and Irrigation (MW&I)
ii.
Kenya Bureau of Standards (KEBS)
iii.
Ministry of Health (MoH)
iv.
The National Environment Management Authority (NEMA) among others.
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However all these bodies are guided by the set international standards published by The
WORLD HEALTH ORGANISATION (WHO). The first WHO document dealing specifically
with public drinking-water quality was published in 1958 as International Standards for
Drinking-Water. It was subsequently revised in 1963 and in 1971 under the same title. In 1984–
1985, the first edition of the WHO Guidelines for Drinking Water Quality (GDWQ) was
published in three volumes: Volume 1, Recommendations; Volume 2, Health criteria and other
supporting information; and Volume 3, Surveillance and control of community supplies.
Second editions of these volumes were published in 1993, 1996 and 1997, respectively.
Addenda to Volumes 1 and 2 of the second edition were published in 1998, addressing selected
chemicals. An addendum on microbiological aspects reviewing selected microorganisms was
published in 2002.
1.2 PROBLEM STATEMENT
The population of Kenya has undergone a steady increase over time. According to the 2010
revision of the World Population Prospects, the total population was 40,513,000 in 2010
compared to only 6,077,000 in 1950. Of this, 30% have access to piped water. The current rate of
urbanization in the country is 3.2% with Nairobi slightly higher with 4.2%.This growth has
overstretched the already scarce water resources. In places where there is no piped water
alternative sources of water have to be obtained.
These alternatives depend on uses and location. Places with constant and abundant rainfall, water
harvesting systems are adopted as alternative sources. Boreholes are drilled to tap underground
water in places with aquifers or known water tables conditions and levels. In coastal and salty
lake regions, clean water is obtained by removal of salt and other mineral from saline water in a
process known as desalination. Stream water has also been embraced in highland areas with
permanent streams
The study done in lower Kabete area (a mainly residential area in Kiambu county, only 17km
from Nairobi’s central business district) showed that people have turned to drilling boreholes
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and fetching water directly from streams as their preferred alternative .In most or almost all cases
the quality of this water has not been tested despite the fact that it is subjected to the most quality
sensitive water use i.e domestic consumption. The only ‘test’ done is just inspection by the eye,
the criteria being ‘if it is clear it is clean and safe for human consumption. some don’t even
bother treating the water by using disinfectants available in the market e.g waterguard or even
simply boiling. Its not rare to just be walking past a stream and seeing somebody squatting at its
banks taking a drink using his/her hands. This begs the question “how safe are the people who
have turned to the streams and ground water from boreholes in this area?”
1.3 Objectives of the study
The main objectives of this quality comparison study are:
i.
To test the ground water quality parameters in the scientifically correct manner
ii.
To test surface water from the streams in the same way
iii.
To compare the two sources and give an advice on which one is better
At the end of the study the results should be able to be used as a tool for sensitization of the
lower kabete residents
CHAPTER TWO
2) LITERATURE REVIEW
Water is essential for life. Most animals and plants contain more than 60 % water by volume.
More than 70 % of the Earth's surface is covered with about 1.36 billion cubic kilometers of
water. Undoubtedly, water quality has tended to take a back seat compared to water quantity in
the provision of water in our country in an environment of limited potable water resources. But
proper water quality management will obviate the need to spend huge resources to address
waterborne diseases which contribute the largest percentage of bed occupancy in our hospitals.
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The NWQMS (National Water Quality Management Strategy) will be the bench mark not only
for the protection of our water resources from pollution but also for ensuring the water provided
to the consumer is safe thus not harmful to health.
2.1 GROUND WATER
This is water that infiltrates into the soil and rock thus making an aquifer. Almost half of
Kenyans’ water comes from ground water. Ground water can be almost pure but this water once
collected should be disinfected before being supplied to consumers. It is important for several
tests to be carried out before distributing the water. However it has been proven that the height of
ground water table or wells can determine the extent of the pollution. The deeper the well, the
better the quality of water. Ground water is susceptible to contaminants that are natural and
others caused by human activities or pollution.
2.1.1 Natural contaminants
As ground water moves throw the ground it comes into contact with rocks and soils that have
different mineral compositions and salts that depending on the quantity may be harmful for
human consumption such as;
i.
Magnesium
ii.
Chlorides and
iii.
Calcium; among others.
Other elements that are dissolved in some ground waters include;
i.
Arsenic
ii.
Boron
iii.
Selenium and
iv.
Radon which is a gas formed by the natural breakdown of radioactive uranium in soil.
2.1.2 Contaminants due to Human activities and pollution
a) Landfills and uncontrolled Hazardous Waste
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Landfills are places where waste is taken and buried. It is a requirement that they have protective
layer on the bottom .sometimes these layers are either omitted deliberately or crack with time.
Through these cracks hazardous wastes is able to reach ground water and contaminating it
b) Use of agricultural Chemicals
Millions of tons of fertilizers and pesticides (e.g., herbicides, insecticides, fungicides) are used
annually for crop production. In addition to farmers, homeowners, businesses (e.g. golf courses),
utilities, and municipalities use these chemicals. A number of this dissolved pesticides and
fertilizers (some highly toxic) have entered and contaminated ground water following normal
repeated use. Some pesticides remain in soil and water for many months to many years. Another
potential source of ground water contamination is animal wastes that percolate into the ground
from farm feedlots. Feedlots should be properly sited and wastes should be removed at regular
intervals.
c) Septic systems and other pipelines
An improperly designed, located, constructed, or maintained septic system can leak. Sewerage
contains bacteria, viruses, household chemicals, and other contaminants which find their way
into the groundwater through these leaks causing serious problems. Other pipelines carrying
industrial chemicals and oil brine have also been known to leak, especially when the materials
transported through the pipes are corrosive
d) Storage tanks
Industries use both underground and aboveground storage tanks to store petroleum products and
other chemical substances. If an underground storage tank develops a leak, which commonly
occurs as the tank ages and corrodes its contents can migrate through the soil and reach the
ground water. Tanks that meet state standards for new and upgraded systems are less likely to
fail, but they are not full proof. Abandoned underground tanks pose another problem because
their location is often unknown. Aboveground storage tanks can also pose a threat to ground
water if a spill or leak occurs and adequate barriers are not in place.
e) Atmospheric contaminants
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Ground water is just part of the larger hydrological cycle. as it is the case in all systems, a
problem in one part of the system is highly likely to trickle to other parts. Contaminations in
surface water and in the atmosphere finds its way into ground water reservoirs
(www.groundwater.org/get-informed/groundwater/contamination )
f) Wells
There are many types of wells drilled for varied purposes. These wells pose a great danger to our
ground water. Some of these wells are ;
i.
Drainage wells:- are used in wet areas to help drain water and transport it to deeper soils.
This drained water may contain agricultural chemicals and bacteria.
ii.
Injection wells:- are used to collect storm water runoff, collect spilled liquids, dispose of
Wastewater, and dispose of industrial, commercial, and utility wastes.
iii.
Improperly Constructed/maintained Wells:-These wells can act as a conduit through
which contaminants can reach an aquifer if the well casing has been removed, as is often
done, or if the casing is corroded.
iv.
Abandoned wells:- In addition, some people use abandoned wells to dispose of wastes
such as used motor oil. These wells may reach into an aquifer that serves drinking supply
wells. Abandoned exploratory wells (e.g., for gas, oil, or coal) or test hole wells are
usually uncovered and are also a potential conduit for contaminants.
g) Mining activities
Active and abandoned mines can contribute to ground water contamination. Precipitation can
leach soluble minerals from the mine wastes (known as spoils or tailings) into the ground water
below. These wastes often contain metals, acid, minerals, and sulfides.
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Illustration 1: Ground water contamination
2.2 SURFACE WATER
2.2.1 POTENTIAL SURFACE WATER POLLUTANTS
a. Eutrophication
This is the process by which a body of water acquires a high concentration of nutrients,
especially phosphates and nitrates. This can be a problem in marine habitats such as lakes as
it can cause algal blooms. Fertilizers are often used in farming, sometimes these fertilizers runoff into nearby water causing an increase in nutrient levels. The algae may use up all the oxygen
in the water, leaving none for other marine life. The bloom of algae may also block sunlight from
photosynthetic marine plants under the water surface. Some algae even produce toxins that are
harmful to higher forms of life. This can cause problems along the food chain and affect any
animal that feeds on them.
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b. Toxic compounds
Toxic compounds which result in destruction or inhabitation of biological activity water such as
heavy metals, phenols, detergents, pesticides and radio isotopes. These substances are mostly
from industrial waste and human activities such as agriculture (FCE 581 lecture notes). Heavy
metals, such as; lead, cadmium, and mercury. Lead was once commonly used in petrol, though
its use is now restricted in some countries. Mercury and cadmium are still used in batteries
(though some brands now use other metals instead). Until recently, a highly toxic chemical
called Tributyltin (TBT) was used in paints to protect boats from the ravaging effects of the
oceans. Ironically, however, TBT was gradually recognized as a pollutant: boats painted with it
were doing as much damage to the oceans as the oceans were doing to the boats.
The best known example of heavy metal pollution in the oceans took place in 1938 when a
Japanese factory discharged a significant amount of mercury metal into Minamata Bay,
contaminating the fish stocks there. It took a decade for the problem to come to light. By that
time, many local people had eaten the fish and around 2000 were poisoned. Hundreds of people
were left dead or disabled.
Radioactive waste (or nuclear waste) is a material deemed no longer useful that has been
contaminated by or contains radionuclides. Radionuclides are unstable atoms of an element that
decay, or disintegrate spontaneously, emitting energy in the form of radiations . People view
radioactive waste with great alarm—and for good reason. At high enough concentrations it can
kill; in lower concentrations it can cause cancers and other illnesses.
The biggest sources of radioactive pollution in Europe are two factories that reprocess waste
fuel from nuclear power plants: Sellafield on the north-west coast of Britain and Cap La Hague
on the north coast of France. Both discharge radioactive waste water into the sea, which ocean
currents then carry around the world. Countries such as Norway, which lie downstream from
Britain, receive significant doses of radioactive pollution from Sellafield. The Norwegian
government has repeatedly complained that Sellafield has increased radiation levels along its
coast by 6-10 times. Both the Irish and Norwegian governments continue to press for the plant's
closure. (www.pollutionissues.com)
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c. Substances that consume dissolved oxygen
There are two categories of these substances
i.
Inorganic reducing agents which exert a chemical oxygen demand(COD)
ii.
Organic matter which exerts a biological oxygen demand(BOD)
The chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of
organic compounds in water. Most applications of COD determine the amount of organic
pollutants found in surface water (e.g. lakes and rivers), making COD a useful measure of water
quality. It is expressed in milligrams per liter (mg/L), which indicates the mass of oxygen
consumed per liter of solution.
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic
biological organisms in a body of water to break down organic material present in a given water
sample at certain temperature over a specific time period. This is not a precise quantitative test,
although it is widely used as an indication of the organic quality of water. This is not a precise
quantitative test, although it is widely used as an indication of the organic quality of water
Oxygen depletion means that oxygen is used up faster than it is replenished. Fish and other
aquatic life die while the bacteria thrive in such conditions. Oxygen depletion occurs when
biodegradable matter is released into water, and in the process of breaking it down, it uses up all
the oxygen in the water. Once this has been reached, bacteria grow and produce harmful
substances like toxins, making the water polluted
d. Pathogens
These are harmful, disease causing microorganisms that may be present in the water. Water
contaminated with pathogenic microorganisms is a major avenue for the spread of infectious
diseases. Many diseases may be transmitted via a fecal-oral route, occurring when human fecal
matter is ingested through drinking contaminated water. Water is an important medium for
transmitting disease as contamination with excreta can lead to ingestion of fecal matter. The
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likelihood of acquiring a waterborne infection increases with the level of contamination by
pathogenic microorganisms. However, the relationship is not necessarily a simple one and
depends very much on factors such as infectious dose and host susceptibility. (WHO, 2004 b)
e. thermal pollutants
Thermal pollution is the degradation of water quality by any process that changes the ambient
water temperature. A common cause of thermal pollution is the use of water as
a coolant by power plants and industrial manufacturers. When water used as a coolant is returned
to the natural environment at a higher temperature, the change in temperature
decreases oxygen supply and affects ecosystem composition. Urban runoff–storm
water discharged to surface waters from roads and parking lots can also be a source of elevated
water temperatures.
When a power plant first opens or shuts down for repair or other causes, fish and other organisms
adapted to particular temperature range can be killed by the abrupt change in water temperature
known as "thermal shock." Elevated temperature typically decreases the level of dissolved
oxygen of water. This can harm aquatic animals such as fish, amphibians and other aquatic
organisms. Thermal pollution may also increase the metabolic rate of aquatic animals, as well as
enzyme activity, resulting in these organisms consuming more food in a shorter time than if their
environment were not changed.
Releases of unnaturally cold water from reservoirs can dramatically change the fish and macroinvertebrate fauna of rivers, and reduce river productivity. Example In Australia where many
rivers have warmer temperature regimes, native fish species have been eliminated, and macroinvertebrate fauna have been drastically altered.
f. Substances that hinder re-oxygenation
Water bodies normally undergo natural recovery. Self purification of rivers depends heavily on
biochemical reactions brought about by activities of microorganisms like bacteria, which when
given sufficient dissolved oxygen utilize organic matter as food and break down complex
compounds to simpler and comparatively harmless end products. This process is made difficult
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by oils, greases and detergents that form a protective film on the water surface and as a result
hindering replenishment of oxygen supply for self purification. Usually the form of surface water
bodies hardest hit by this form of pollution are seas and oceans that are used for routine shipping.
It is assumed that tanker accidents are the greatest cause of spillage on the contrary, over 70% of
oil pollution at sea comes from routine shipping and from the oil people pour down drains on
land. However, what makes tanker spills so destructive is the sheer quantity of oil they release at
once — in other words, the concentration of oil they produce in a localized part of the marine
environment. The biggest oil spill in recent years (and the biggest ever spill in US waters)
occurred when the tanker Exxon Valdez broke up in Prince William Sound in Alaska in 1989.
Around 12 million gallons (44 million liters) of oil were released into the pristine wilderness
g. Inert solids
Water in streams picks up inert solids, both suspended and dissolved. if highly concentrated they
blanket the bed of a stream preventing growth of certain microorganisms.eg china clay, silt etc.
this affects the quality of water especially it’s color, turbidity, taste and odour and makes it less
desireable to drink
2.3 WATER QUALITY PARAMETERS
The term water quality parameters refer to those characteristics of water upon which the quality
of water can be determined. These parameters are physical, chemical and biological parameters
2.3.1 Physical parameters
Physical parameters are the characteristics of water that are readily detectable by the senses.
They include;
i.
Colour
ii.
Taste and odour
iii.
Temperature
iv.
Turbidity
v.
Solids
vi.
Electrical conductivity
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2.3.1.1 Colour
Water in small quantities appears colourless to the naked eye. However, large bodies of water
have a deeper blue colour which gets darker with depth. The blue colour is an intrinsic property
and is caused by the selective absorption and scattering of white light.
(Color of water – Wikipedia, the free encyclopedia )
Water from different sources may have different colours either apparent or true. Apparent colour
which is caused by suspended material in water that absorbs and scatters visible light can be
eliminated using coagulation and gravity sand filtration. True colour is caused by dissolved
organic matter that usually includes aromatic chemicals such as lignin or humic and fulvic acid.
Coagulation and flocculation with hydrolyzing metals such as aluminum in alum will allow some
of the true colour to be removed by sand filtration. However, oxidation, activated carbon
adsorption and membrane filtration technologies like ultra filtration, nanofiltration and reverse
osmosis are considered the most efficient methods to remove most of the soluble organic-related
colour from water supplies.
Several tests can be carried out to determine the colour of water from a source the most common
one being the Nessler cylinder. Where the level of discolouration is matched against a standard
Hazen disc and measured in degrees hazen. Green colour for instance may be an indication of
algae growth. According to (World Health Organization 2006)most people can detect colours
above 15 true colour units (TCU) in a glass of water. Levels of colour below 15 TCU are usually
acceptable by consumers, but acceptability may vary. High colour could also indicate a high
propensity to produce by-products from disinfection processes. No health-based guideline value
is proposed for colour in drinking-water.
2.3.1.2 Taste and Odour
Tastes and odours are major factors influencing the consumers' perception of drinking water
quality. Consumers generally believe that if their drinking water tastes or smells 'off ', then it is
probably not safe to drink. This is because unfamiliar or unpleasant tastes or odours and
appearance represent the only tangible and instant means for consumers to gauge the quality of
water for drinking, cooking, bathing and washing purposes. the sources of the tastes and odours
could be natural or caused by man. Algae and decaying vegetation are the principal substances
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related to natural sources. Agricultural activities domestic and industrial waste-on the other hand,
are the most common sources of induced tastes and oduors.
Table 01: sources of odours
Odour
Source
Chlornious
Disinfection by chlorine
Oily
Hydrocarbons, volatile organic compounds
Septic
Low dissolved oxygen
Phenolic
Industrial contamination ,gasoline
contamination
Chemical
Organic chemicals, industrial contamination
Earthy/musty
Algae growth
Table 02: sources of taste
Taste
Source
Salty
Chlorides
Bitter
Foaming agents
Metallic
Iron , copper
Bitter metallic
Manganese, low ph
The threshold odour test has become the standard control test for several reasons. First, it is safer
and does not involve the potential health hazard of tasting untreated water. Second, tastes and
odours are closely related and removal of odours usually results in the removal of
tastes. No method of controlling taste and odour will necessarily be successful in all waters at all
times and under all conditions. However, the most common practices include oxidation, chlorine
dioxide, potassium permanganate, ozone, and adsorption on activated carbon. A mixture of
methods is the correct approach because very frequently the success of each treatment depends
on the proper functioning of one or more processes.
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2.3.1.3 Turbidity
Turbidity is defined as the degree of clearness of water or the level of cloudiness of a water
sample. It is caused by the presence of suspended particulates arising mainly from urban runoff,
waste discharge, algae growth or sediments from erosion.
It is measured by use of a turbidimeter or nephelometer which work by the principle of shining
light through the samples in question. This measure is reported in nephelometric turbidity units
(NTU). Although the main impact of turbidity is aesthetic, it is also essential to eliminate the
turbidity of water in order to effectively disinfect it for drinking purposes. According to the
World health Organization (WHO), the maximum allowable turbidity in drinking water should
not be more than 5 NTU and should ideally be below 1 NTU.
(WHO's Drinking Water Standards 2013)
2.3.1.4 Temperature
Water temperature is the measure of how warm or cold water is. It impacts on the chemical and
biological characteristics of water. Changes in temperature have been proven to alter the
following;
i.
Density of water
ii.
Surface tension
iii.
Specific conductivity
iv.
Dissolved oxygen
v.
Viscosity of water
vi.
Chemical oxygen demand (COD)
vii.
Biochemical oxygen demand(BOD)
viii.
Photosynthesis of aquatic plants
ix.
Metabolism of aquatic organisms
The temperature of drinking water has no health effect and hence no standards have been set. It
becomes an issue of personal preference.
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2.3.1.5 Solids
Solids in water are divided into two main categories;
• Total dissolved solids (TDS)
• Total suspended solids (TSS)
Total dissolved solids are a measure of all inorganic and organic substances contained in a liquid
in molecular, ionized or micro-granular suspended form. Total dissolved solids are normally
discussed in fresh water systems as salinity comprises of some of the ion constituting the
definition of TDS. The principal application of TDS is in the study of water quality for streams,
rivers and lakes and although TDS is not considered a primary pollutant, it is used as an indicator
of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a
broad array of chemical contaminants. (Total dissolved solids-Wikipedia the free encyclopedia)
Total suspended solids refer to the dry weight of solids that would not go through a filter of
specific aperture size. It is measured by passing the sample in question through a pre-weighed
filter, letting it dry and then reweighing it.
2.3.1.6 Electrical conductivity
Electrical conductivity is the ability of a substance to conduct an electrical current, measured in
Microsiemens per centimeter(mS/cm). Ions such as sodium, potassium, and chloride give water.
Conductivity can be an indicator of the amount of dissolved salts in a sample. Conductivity often
is used to estimate the amount of total dissolved solids (TDS) rather than measuring each
dissolved constituent separately
(Farrell-Poe, Water Quality & Monitoring, 2005)
2.3.2 Chemical parameters
2.3.2.1 PH / Hydrogen ion concentration
Ph is the measure of acidity or alkalinity of water. It is a measure of hydrogen ions [H+]
expressed by the function pH given by;
16 | P a g e
PH= -log10 = log10 (1/ [H+]
A value of 7 is the neutral value .Any value below indicates acidity and any above 7 indicates
alkalinity. The range of natural pH in fresh waters extends from around 4.5 for upland water to
over 10.0 in waters where there is intense photosynthetic activity by algae. However, the most
frequently encountered range is 6.0 – 8.0.
Illustration 2: ph ranges
2.3.2.2 Chlorides
Chlorides are widely distributed in nature as salts of sodium (NaCl), potassium (KCl), and
calcium (CaCl2). All natural waters have chlorides, the concentrations varying very widely and
reaching a maximum in sea water (up to35000 mg/l). In fresh waters the sources include soil and
rock formations, sea spray and waste discharges. Sewage contains large amounts of chloride, as
do some industrial effluents.
17 | P a g e
Chloride concentrations in excess of about 250 mg/litre can give rise to detectable taste in water,
but the threshold depends upon the associated cations. Consumers can, however, become
accustomed to concentrations in excess of 250 mg/litre. No health-based guideline value is
proposed for chloride in drinking-water.
( http://www.who.int/water_sanitation_health)
2.3.2.3 Hardness
Water that is considered hard is high in dissolved minerals, specifically calcium and magnesium.
As the concentration of these minerals increase, the water becomes harder. Other ions which
occur in relative low concentrations but are still responsible for water hardness are iron,
manganese, aluminum and zinc.(Water hardness, 2013)
There is no health risks associated with hard water. On the contrary, people who take hard water
throughout their lifetime have a lower rate of cardiovascular disease.
However, there are problems associated with hard water, these include
 Grey straining of washed clothes
 Scum on wash and bath water following use of soap or detergent
 Reduced lathering of soaps
 Build-up of scale on electric heating elements and boilers
 Reduced water flow in hot water distribution pipes due to scale build-up
 Accumulation of whitish- gray scale in tea kettles and other containers used to
boil water
Table 03; hardness table
Concentration of CaCO3
Degree of hardness
0 – 75 mg / l
Soft
75 – 150 mg / l
Moderately hard
150 – 300 mg / l
Hard
300 mg / l and more
Very Hard
18 | P a g e
Low level of hardness can be easily removed by boiling. High degree of hardness is removed by
the addition of lime. This method has also the benefit that iron and manganese contents are
removed and suspended particles including micro- organism are also reduced.
CaCO3 + CO2 + H2O → Ca2+ + 2HCO3-
2.3.2.4 Alkalinity
Alkalinity is a measure of the amount of natural water required to neutralize acid added to it.
There are three main forms of alkalinity which are bicarbonates, carbonates and hydroxides
which are converted to carbonic acid. At pH 10, the hydroxide present reacts to form water,
while at pH 8.3 carbonates are converted to bicarbonates and finally at pH 4.5 it is certain that all
carbonates and bicarbonates are converted to carbonic acid.
Alkalinity is of interest to water engineers in that it is a factor concerned in the computation of
the so-called Langelier "Saturation Index" which relates to the corrosion of or deposition of scale
in distribution networks. (Environmental Protection Agency, 2001)
2.3.2.5 Dissolved oxygen
Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in an aqueous
solution. Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid
movement), and as a waste product of photosynthesis. The prime requirements for DO arise in
connection with fish life and it is generally true that if water quality is suitable for fish it will also
meet the criteria for most if not all other beneficial uses and be of good ecological status.
Dissolved oxygen levels fluctuate seasonally and over a 24- hour period. It varies with water
temperature and altitude. Cold water holds more oxygen than warm water; water holds less
oxygen at higher altitudes. Clean waters are normally saturated with Dissolved Oxygen, but such
D.O can be rapidly removed by the oxygen demand of organic wastes. Water with oxygen tends
to have a pleasant taste and no odour.
2.3.2.6 Fluoride
Fluoride comes from minerals such as fluorspar but in some countries fluoride is artificially
added to water .when present in optimum concentration of 0.8 to 1.2mg/l (depending on water
19 | P a g e
intake per day), fluoride minimizes dental caries. However, when present in excess
concentrations, it is responsible for adverse effects starting from mild mottling of teeth
(yellowish discoloration) (FCE 481lecture notes 2013)
Over many years, fluoride can build up in people’s bones, leading to skeletal fluorosis
characterized by stiffness and joint pain. In severe cases, it can cause changes to the bone
structure and cause crippling effects. Infants and young children are most at risk from high
amounts of fluoride as their bodies are still growing.
2.3.2.7 Nitrates
Nitrate (NO3) is a naturally occurring form of nitrogen found in soil. Nitrogen is an essential
compound to the human body and also to the crops in order to sustain high yield. Almost all
inorganic nitrate salts are soluble in water thus making drinking water unsafe for consumption.
When water containing high levels of nitrates is consumed, nitrite is absorbed in the blood and
haemoglobin converted to mathemoglobin which doesn’t carry blood efficiently thus resulting in
reduced oxygen quantity in vital tissues such as the brain. Intense mathemoglobinemia results to
brain damage or death. Animals should not drink water with more than 100 mg/l NO3 –N
(nitrate-nitrogen) as it’s harmful. Nitrates discharge standards in natural water should not exceed
50mg/l as per the WHO standards.
Nitrates are common in;
i.
Animal feedlots,
ii.
N-fixation from atmosphere by legumes, bacteria and lightning,
iii.
Septic systems,
iv.
Waste water and sludge
v.
Fertilizers and manure
It’s important then to protect the water supply points to avoid contamination; high nitrate levels
are often associated with poorly constructed or improperly located wells. Wells should be located
uphill and at least 100 feet away from feedlots, septic system, barnyards and chemical storage
facilities and they should be sealed or cap abandoned to prevent contaminations
20 | P a g e
2.3.3 MICROBIOLOGY AND BACTERIOLOGICAL ASPECTS
Microorganisms are usually very small living organisms which can only be seen with the help of
a microscope. Many species of the organisms have been identified and studied extensively.
Engineers are interested in microorganisms that are involved in the following
i.
Causing water-borne diseases
ii.
Decomposition and stabilization of organic matter
iii.
Useful reactions that are gainful eg: industrial production of alcoholic beverages,
fermented dairy products, vitamins, enzymes etc
Of particular interest to public health engineers is
i.
Cow pathogens find their way into water
ii.
Their movement from one point to another
iii.
Their changing behavior with changing environmental conditions
Bacteria are responsible for most of the most devastating water-borne diseases in addition they
play a major role in biodegradation. There are several characteristics bacterial posses that
enable us to identify them and manipulate their numbers as desired .They include;
2.3.3.1 Distinctive characteristics of bacteria
a) Shape
Bacteria are either spherical(cocci),rod shaped(bacilli), spiral shaped or common
shaped(vibrio).they can also e distinguished by presence of tail-like features which enable
mobility , called flagella which differ in configuration and number for different species.
b) Size
Range in diameter from 0.3 - 2μm and length 1 - 2μm for rods and diameter 0.6 - 2μm and length
20 - 50μm for spirals.
21 | P a g e
c) Antigenic
If bacteria and other pathogens try to enter into our bodies, our bodies produce substances which
fight with the invading foreign organisms called antigens. The substances produced are called
antibodies. Antibodies are very specific for the particular antigen. This enables us to recognize a
particular type of bacteria.
d) Nutritional
Bacteria have different feeding characteristics e.g ;saprophytic bacteria feed on dead rotting
matter while C-autotroph utilize mineral carbon as their food and build cells from it.
e) Cultural
Refers to where they live and grow eg
i.
Temperature – different types do well in different temperature 0 – 10o :
ii.
PH – most do best between 6 – 8, but others at extreme pH e.g thiobacillas best pH
around 1
iii.
Salinity – again most do best in normal salinity but halophiles do best at salinity
>6,000mg/l
f) Biochemical
Refers to metabolism
i.
Aerobic – require oxygen for their metabolism
ii.
Anaerobic – do not require oxygen for their metabolism
iii.
Facultative - will do in both situations
In addition to pathogens, all humans excrete billions of microorganisms each day in their faeces
and urine. These mostly harmless organisms are excreted y both infected and normal people and
22 | P a g e
in much larger numbers than pathogenic organisms, which means that chances of finding them
in water are much higher than that for pathogens. These can be used as indicators of the potential
presence of pathogens in water.
2.3.3.2 Rationale for the use of indicator organisms
Direct search for specific pathogens in drinking or public waste supplies, particularly for routine
monitoring of the water quality is impracticable. The main reasons are;
i.
Large volumes of water will need to be examined before any pathogens can be isolated.
This is not only expensive but the time required would usually render the results useless.
ii.
The methods for isolating and enumerating specific pathogens are complex and time
consuming.
iii.
Pathogens tend to die relatively fast in water compared to indicator organisms.
iv.
Reliable, faster, cheaper and simpler methods of assessing the bacteriological quality of
water have been developed. These methods use indicator organisms; the rationale is that
the absence of indicator organisms almost certainly confirms the absence of pathogens in
the tested water sample .
2.3.3.3 Characteristics of good indicator organisms
They include:
i.
Must be a reliable presence of the potential presence of specific contaminating
organisms both in natural and treated waters and react to the natural aquatic
environment and treatment processes, especially disinfection is substantially the
same manner and degree as the pathogens.
ii.
Must be identifiable by simple analytical procedures that provide the wanted
information quickly and economically.
iii.
Must lend themselves to numerical evaluation as well as qualitative distinction.
iv.
Must be present in much larger numbers than pathogens in order to be a sensitive
measure of the potential presence of the pathogens.
23 | P a g e
v.
They should survive longer than pathogens in water and be more resistant to
disinfection.
Several indicator organisms can be used in bacteriological examination of water although no
type satisfies all the above requirements. Some justify almost all of them for instance E-coli.
((FCE 481 lecture notes 2013)
3) CHAPTER 3: METHODOLOGY AND APPROACH.
3.1 INTRODUCTION
This chapter entails the description of methods and techniques used in collection of data, analysis
and experimentation which helps in accomplishing the project’s objective being assessment of
the ground water quality and comparing this to the surface water quality to see which one is the
better alternative to the unreliable tap water supply . For this to be achieved, the following
approaches were used:3.2 Sampling
3.2.1 Guidelines for sampling point selection
a) Its proximity and availability to the people living in the area – It is a natural human trait
to rely on resources that are closest to them. Water sources that are close to people are
the ones that are most likely to be used for day to day purposes like domestic use and
drinking
b) Easy accessibility of the sampling station (for the streams) –if points are accessible
easily during sampling it shows then that these points are more likely to be the water
fetching points for the residents
c) The distance between boreholes should vary significantly - the geological characteristics
of an area influences ground water quality. Taking samples from close by boreholes
would increase chances of the water being from the same aquifer (it would be like taking
samples from two taps on the same tank)
24 | P a g e
3.2.2 Sampling process
Care was taken to obtain samples which gave a true representation of the existing conditions and
handled in such a way as to prevent deterioration and contamination before they arrived at the
laboratory. The sample bottles were washed clean and rinsed with distilled water prior to
collecting the samples. Water from the sampling points was used to rinse the bottle twice before
the sample was collected.(carefully sterilized sampling bottles were used for bacteriological
examination in order to avoid any form of contamination).
The types of samples collected were grab samples. This was because the sources were known to
be constant in composition over a long period of time. One litre of each sample was collected for
the purpose of the study. Each sample was clearly marked with a permanent marker and the point
of collection noted.
The samples were taken to the laboratory immediately after sampling and the urgent tests ( such
as Dissolved oxygen , plate count and pH) were taken immediately in the laboratory to avoid any
more sources of error taking account of variations due to transportation of samples. It would
have been more appropriate to measure the Dissolved oxygen and pH on site but it wasn’t
possible due to lack of equipment and inadequate resources. The samples were then stored in the
refrigerator overnight and the chemical analysis conducted within the next 24 hours.
The following water points were identified for the purpose of the study:
Stream A –sample 1
Stream B – sample 2
Borehole 1 – sample 3
Borehole 2 – sample 4
3.2.3 Laboratory tests
Laboratory tests were conducted after sampling. The tests were divided into;
a. Physical tests
b. Chemical analysis
c. Bacteriological examination
25 | P a g e
3.2.3.1 Physical tests conducted
The physical tests carried out were:
i.
Turbidity (Turbidimeter )
ii.
Colour (Lovibond comparator)
iii.
Total suspended solids(TSS)
3.2.3.2 chemical tests conducted
i.
pH (pH meter)
ii.
Nitrates
iii.
Chloride (silver nitrate)
iv.
Iron
v.
Hardness (EDTA solution)
vi.
Alkalinity
vii.
Fluoride
viii.
Dissolved oxygen
For bacteriological examination, the standard plate count method was used
4) RESULT ANALYSIS
4.1 Tabulated lab results
4.1.1
PARAMETER
DISSOLVED
Table 4.1.1: lab results table
SAMPLE
SAMPLE SAMPLE 3 SAMPLE 4 WHO
1
2
(STREAM A)
(STREAM B)
4.79
5.82
UNITS
REMARKS
Mg/l
All samples
(BOREHOLE 1) (BOREHOLE 2) GUIDELINES
5.76
5.26
>2.0
OXYGEN
HARDNESS
satisfactory
68
80
140
304
<500
mgCaco3/ All samples
l
ALKALINITY
119
67
48
41
<500
satisfactory
mgCaco3/ All samples
26 | P a g e
SOLIDS
23.7
27.0
21.0
112
<1500
l
satisfactory
Mg/l
All samples
satisfactory
IRON (Fe+)
0.8
0.2
0.2
0.2
<0.3
mgFe+/l
Sample 1
unsatisfactory
PH
7.02
7.37
6.5
6.57
6.5 – 8.5
All samples
satisfactory
CHLORIDE
COLOUR
81
10
82
15
133
5
248
5
<250
<15
Mg/l
All samples
chloride
satisfactory
0
All samples
hazen
satisfactory
TURBIDITY
5.5
7.5
1.5
0.6
<5
FTU
Stream
samples(1and
2)
unsatifactory
FLOURIDES
NITRATES
1.1
3
0
2
0
6
0
9
1.5
<10
Mg/l
All samples
flouride
satisfactory
Mg/l
All samples
satisfactory
PLATE
COUNT
91
65
28
32
Colonies/
unsatisfactory
ml
27 | P a g e
4.2 Graphical representation and discussion of results
4.2.1 Dissolved oxygen
7
6
5
4
3
2
1
0
sample 1
sample 2
sample 3
sample 4
who
Chart 1:Dissolved oxygen chart
The dissolved solids ranged from 4.79 to 5.82mg/l. Dissolved oxygen is required for the water to
be acceptable by consumers. Therefore, a higher level of dissolved oxygen is suitable usually
above 2mg/l. It was also noted that the highest and lowest values were both from streams(surface
water) proving that a stream’s path and characteristics influence its DO levels
28 | P a g e
4.2.2 Hardness
600
500
400
300
200
100
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 2: Hardness chart
All the samples tested were within the acceptable range of 500mg Caco3/l for drinking water.
However, samples from boreholes (ground water) exhibited significantly higher values than
surface water proving that ground water in the area is harder than surface water. The table below
was used to categorize the samples'
4.2.2.1 Hardness table
Range (mgCaCO3/l)
Hardness level
Sample in the category
0-50
Soft
_____
50-100
Moderately soft
Sample 1 (68) sample 2 (80)
100-150
Slightly hard
sample 3 (140)
150-200
Moderately hard
_____
200-300
Hard
_____
Over 300
Very hard
Sample 4 (304)
29 | P a g e
4.2.3 Alkalinity
600
500
400
300
200
100
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 3: Alkalinity chart
All samples were below 500mg Caco3/l which is acceptable .On the other hand it is good for
alkalinity of a water sources to be above 10mgCaco3/l in order to buffer against rapid pH
changes. The streams showed a greater potential to buffer with an alkalinity of 119 and
67mgCaco3/l compared to ground water whose alkalinity was 41 and 48mgCaco3/l.
30 | P a g e
4.2.4 solids
1600
1400
1200
1000
800
600
400
200
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 4: Solids chart
From the TDS test conducted, all samples had amounts of solids far below the set standards of
1500mg/l .They ranged from 112 – 270 mg/l. On comparison it was noted that surface water had
more solids(237 and 270mg/l) than ground (112 - 210mg/l) which was expected due to exposure
and flow of the streams
31 | P a g e
4.2.5 Iron
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 5: Iron chart
Three of the four samples were below the stipulated maximum of 0.3 mg Fe+/l reading 0.2 mg
Fe+/l .Sample 1 which was taken from a stream had a value of 0.8 which is not acceptable. Iron
is not a great risk to human health but it could pose problems to people with existing heart and
kidney problems. It also imparts unpleasant taste in water (phe 481 lecture notes)
32 | P a g e
4.2.6 Chlorides
300
250
200
150
100
50
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 6: Chlorides chart
All samples had acceptable chloride levels ranging from 81 – 248mg/l. sample 4 from a borehole
was so close to the allowable maximum value of 250mg/l. It is advice-able to test more
frequently to keep the levels on check. The borehole water samples had higher chloride content
of 133 & 248mg/l while that of stream water had chloride content of 81 & 82mg/l. Due to
dissolved content of mineral rocks, ground water as expected has higher chloride content
compared to surface water. Amount of chloride in drinking water has less health concern.
However if chloride content is higher than the acceptable amount, water may have a salty taste.
33 | P a g e
4.2.7 colour
16
14
12
10
8
6
4
2
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 7: Colour chart
Colour is one of the most common and quick method used by people to presume water quality.
All the samples had a colour hazen of between 50 – 150 which is acceptable according to
standards set by Water Services Regulatory Board (WASREB) and WHO. Surface water
samples had higher degree hazens of colour (10 and 15 degrees hazen) compared to ground
water samples (50 hazen)Presence of colour in water is indicative of coloured organic matter or
high concentration of coloured ions in the water. The source of colour in a drinking-water should
be investigated, particularly if a substantial change has taken place.
34 | P a g e
4.2.8 Turbidity
turbidity
8
7
6
5
4
3
2
1
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 8:Turbidity chart
From the turbidimeter readings it was observed that water from the streams were very turbid
sample 1 was a bit off with a reading of 5.5FTU,sample 2 was even more turbid posting a
reading of 7.5 FTU. The standards accept values below 5.0 FTU. Ground water samples had
values of 1.5 and 0.6. Turbidity may be as a result of pollution of the streams upstream both
natural and human caused .Though not a big risk to human health, turbid water would be rejected
by most people and only be taken as a last option.
35 | P a g e
4.2.9 Fluorides
flourides
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
sample 1
sample 2
sample 3
sample 4
WHO
Chart 9: Fluorides chart
Fluoride minimizes dental caries. However, when present in excess concentrations, it is
responsible for adverse effects starting from mild mottling of teeth (yellowish discoloration)
fluoride can build up in people’s bones, leading to skeletal fluorosis characterized by stiffness
and joint pain. it is there very important to test for fluorides to maintain optimum levels usually
between 0.8 to 1.2 mg/l. sample 1 from surface water had 1.1 mg/l fluorides which is desireably
balanced(neither too little or too much).the rest of the samples had zero fluorides which is not
healthy and fluoride should be added artificially.
36 | P a g e
4.2.10 Nitrates
nitrates
12
10
8
6
4
2
0
sample 1
sample 2
sample 3
sample 4
WHO
chart 10: Nitrates chart
Kenya drinking water standards h as set the maximum allowable nitrates concentration at
10mg/l. From the experiments conducted, all samples were acceptable with between 2 – 9 mg/l.
It was noted that ground water in the lower kabete area has higher nitrate content(6 and 9mg/l)
compared to surface water (2 and 3mg/l)
37 | P a g e
4.2.11 pH
PH
9
8
7
6
5
PH
4
3
2
1
0
sample 1
sample 2
sample 3
sample 4
WHO min
WHO max
Chart11: pH chart
Surface water was found to have higher pH values (7.02 and 7.37) compared to ground water
(6.50 and 6.57).This was expected from the alkalinity results obtained pH is generally considered
to have no direct impact on humans. However, long-term intake of acidic water can invariably
lead to mineral deficiencies (Fairweather-Tait and Hurrrell, 1996). Non-health effects are
aesthetic because acidic water tends to be corrosive to plumbing and faucets. Taste may also be
affected by pH
38 | P a g e
4.2.12 plate count
colonies
100
90
80
70
60
50
colonies
40
30
20
10
0
sample 1
sample 2
sample 3
sample 4
Chart 12: plate count chart
The samples were found to have presence of Escherichia Coli bacteria ranging from 28 - 91
colonies/ml. The acceptable limit of total viable counts at 37oC is 100 per ml Adopted from KS
05-459: Part 1:1996). The water samples are therefore within the acceptable range however
disinfection is highly recommended when using this water for drinking. This may include boiling
of the water before using for drinking or treating with disinfectants readily available. Presence of
coliform bacteria in drinking water indicates risk of contracting a water-borne disease. Total
coliform may come from sources other than fecal matter however it should be considered as an
indication
The main objectives of this quality comparison study are:
i.
To test the ground water quality parameters in the scientifically correct manner
ii.
To test surface water from the streams in the same way
iii.
To compare the two sources and give an advice on which one is better
39 | P a g e
Having conducted all the tests for the selected parameters in the scientifically correct manner in
the PHE laboratory the first two have been achieved. The table below is a comparison table
between ground water and surface water derived from the results obtained aimed at achieving the
third objective
Recap:
Stream A –sample 1
Stream B – sample 2
Borehole 1 – sample 3
Borehole 2 – sample 4
4.3 Comparison of results
Table 4.3.1 :comparison table
PARAMETER
Dissolved oxygen
Hardness
REMARKS
SURFACE WATER
GROUND WATER
Sample 1 & 2
Sample 3 & 4
Above the set minimum value
Above the set minimum value
and in the same range as
and in the same range as
ground water
surface water
Below the set maximum and
Below the set maximum but
lower than ground water hence also significantly harder than
better quality in terms of
surface water
hardness
Alkalinity
Within the acceptable
Within the acceptable
standards .sample 1 being
standards. lower than surface
significantly higher and
water
sample 2 was slightly higher
than ground water samples
TDS
Slightly higher than ground
Lower than surface water
water but safe for drinking
40 | P a g e
Iron
Sample 1 was found to be
both samples were satisfactory
unacceptable according to
WHO standards with a value
of 0.8mg/l far much above the
set 0.3mg/l. sample 2 was
within range
PH
Chloride
Slightly alkaline but not above
Slightly acidic but not
8.5 hence acceptable
below6.5 hence acceptable
Significantly lower chloride
Rich in chlorides most
levels were observed
probably due to the mineral
compared to ground water
composition of the rocks in
sources inn the area
the area. sample 1 came very
close to the acceptable
maximum
Colour
Exhibited higher 0hazen of
Low0hazen of colour
colour sample 2 was at the
compared to surface water
maximum but not past it
.colour is only aesthetic and
has almost no health effect.
Turbidity
Very turbid. Both samples
Very low turbidity and
were above the acceptable
therefore better quality than
maximum. This was expected
surface water in terms of this
due to exposure of surface
parameter
water.
Fluorides
Sample 1 had acceptable
Both samples were fluoride
amount of fluorides at 1.1mg/l
deficient
while sample 2 was fluoride
deficient
Nitrates
Lower nitrates concentration
Presence of nitrates was more
compared to ground water
significant but below the
maximum allowable value
41 | P a g e
Plate count
More colonies were counted
Fewer colonies were counted
hence indicating a higher
indicating a lower probability
probability of bacterial
of bacterial contamination
contamination
CHAPTER 5: Conclusions and recommendations
5.1
conclusion
The following conclusions on water consumed by residents of lower kabete area were drawn;
a) The scarcity of piped tap water in the region is a major problem which has led to many
people digging up boreholes. However, this is quite a challenge because people are
digging up boreholes blindly without going to the relevant authorities so as to avoid
more expenses. Lack of this information can lead to water borne diseases especially
when people dig boreholes near latrines. In addition there are rules that stipulate how
many boreholes should be in a specific place and how deep they should be therefore.
Failure to consider this while digging up a borehole, residents may end up not getting
quality water or they may have to dig deeper which eventually ends up being quite
expensive.
b) In the experiments conducted above most of the parameters which could cause serious
health problems were within the set standards of Drinking Water (1996). Therefore it can
be concluded that both ground water and surface water in the area is safe for
consumption once boiled or treated. The high iron levels and turbidity levels are not
harmful to human health, they are just aesthetical and may alter taste of water if they are
too high.
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c) The two water sources under comparison that is ground and surface water both found to
be acceptable and safe according to the set standards Drinking Water (1996) therefore
the choice of the source is up to the consumer guided by availability, convenience,
reliability, preference, financial capability etc
.
5.2 RECOMMENDATIONS
a) The Kiambu county ministry of water together with water service providers should work
on improving reliability of piped ,treated ,safe water for the people of lower kabete
b) Chemical analysis should be carried out on both water sources more frequently at
intervals of maybe 4 months (thrice a year) to ensure that the water consumed is kept on
check against the set standards by WHO and KEBS
c) The coliform count obtained showed a probability of bacterial contamination. All water
should then be boiled or treated before consumption
d) A detailed study of the biological quality of water should be carried out in all sources
in lower kabete since the plate count is just a presumptive test and already indicates a
probability of bacterial contamination. Confirmatory tests should be done to check for
disease causing microorganisms.
e) Sensitize and educate communities living upstream on the importance of proper water use
without compromising water quality in the streams
f) Develop a sustainable national programme on water and sanitation, suitable for lower
kabete
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.
REFERENCES
1) www.nytimes.com, 2013
2) wikipedia.org/wiki/Public health
3) www.groundwater.org/get-informed/groundwater/contamination
4) P K Ndiba FCE 581 lecture notes 2014).
5) www.pollutionissues.com
6) (Color of water - wikipedia, the free encyclopedia. 2012. Www.wikipedia.org.
7) Water quality indicators: Temperature and Dissolved oxygen. 2012.
Www.rampalberta. Org.
8) World Health Organization 2006
9) Alabama water quality information systems. 2013. Www.aces.edu/waterquality.
10) Kenya Drinking water Quality Standards (1996).
11) World Health Organisation (1996) ; Guidelines for Drinking Water Quality , vol.
2,
12) WHO's Drinking Water Standards. 2013. Www.lenntech.com.
13) .(Total dissolved solids-Wikipedia the free encyclopedia
14) (Farrell-Poe, Water Quality & Monitoring, 2005
15) ( http://www.who.int/water_sanitation_health
16) ""water hardness."glendale water and power. 2013.
Www.glendalewaterandpower.com
17) Environmental Protection Agency, 2001
18) J N Gitonga. "lecture Notes(PHE 481 & 482)." 2013.
19) Fairweather-Tait and Hurrrell, 1996.
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6
CHAPTER 6
APPENDIX 1:
Picture 1: sampling in process
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Picture 2: sample collection
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Picture3; samples in the lab
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Picture4: phe lab
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Picture 5: testing in progress
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Picture 6:testing for nitrates
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Picture7:pH/ORP & Nacl Meter
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