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Journal of Environment Pollution and Human Health, 2017, Vol. 5, No. 1, 15-21
Available online at http://pubs.sciepub.com/jephh/5/1/3
©Science and Education Publishing
DOI:10.12691/jephh-5-1-3
Analysis of Microbial Quality of Drinking Water in
Njoro Sub-county, Kenya
Kirianki PR1,*, Othira JO1, Kiruki S2
1Department of Biochemistry and Molecular Biology, Egerton University, 536-21115, Njoro, Kenya
2Department of Physical sciences, Chuka University, 109-60400, Chuka, Kenya
*Corresponding author: philipkirianki@gmail.com
Abstract Drinking water should be free of microbial pathogens so as to be regarded as potable water and safe for
drinking. However, water is prone to fecal contaminants which are the sources of gastrointestinal illnesses. In Njoro
Sub-county, river Njoro and rain water are the primary sources of water which also reduces during dry seasons.
Other water sources include boreholes, dams, springs and wells while in other cases, the residents store water in
household storage containers for future uses. In this study, various water sources and water stored in different
containers in Njoro Sub-County was analyzed for its microbial quality. Various microbial parameters such as total
viable colony counts (TVCC), total coliforms (TC) and fecal coliforms (FC) were evaluated by use of the culture
methods. Most of the water sources were contaminated. TVCC ranged from 0.47 to 1.76 CFU/1mL in water sources
and 0.48 to 2.04 CFU/1mL in domestic storage containers. TC was in the range of between 0.30 to 1.89
CFU/100mL in water sources and 0.59 to 2.47 CFU/100mL in domestic storage containers. The mean FC in water
sources ranged from 0.10 to 1.68 CFU/100mL and from 0.81 CFU/100mL domestic storage containers. Therefore
frequent water testing should be performed by water authorities as recommended by WHO. At households, the
people should employ various water treatment methods and practice safe water handling so as to avoid
gastrointestinal infections.
Keywords: coliforms, water quality, contamination
Cite This Article: Kirianki PR, Othira JO, and Kiruki S, “Analysis of Microbial Quality of Drinking Water in
Njoro Sub-county, Kenya.” Journal of Environment Pollution and Human Health, vol. 5, no. 1 (2017): 15-21.
doi: 10.12691/jephh-5-1-3.
1. Introduction
Microbiological quality of water is measured by the use
of indicator organisms such as TVCC, TC and FC bacteria
[1]. TVCC are also known as total plate count, heterotrophic
plate count or pour plate and are widely used in the
measurements of heterotrophic microorganisms in water
meant for drinking purposes. The heterotrophs consist of
microorganisms such as yeasts, molds, and bacteria which
needs external sources of organic carbon in order to grow.
Some members of this group are opportunistic pathogens
and can cause aesthetic and non-life-threatening diseases
especially in immunosuppressed people as well as
children [1,2].
TVCC therefore, accesses the formation of colonies on
a culture media and hence it is a measure of the overall
bacteriological quality of drinking water in both public as
well as private water systems. The level or recoverability
of heterotrophic organisms using this method depends on the
type of media used, the culture temperatures, age of the
water sample and the duration of the culture. As a result,
high numbers of TVCC bacteria in a distribution system
might be a result re-growth of bacteria that resisted
treatment or alternatively those that were injured during
treatment have recovered. In this case, bacterial re-growth
can lead to devastating effects such as corrosion of pipes
and increased growth of slime and hence the need for
disinfectants [3].
TC comprises of bacterial species of fecal origin as well
as other non-fecal bacteria groups [4]. These microorganisms
are indicative of the general hygienic quality of the water
and potential risk of infectious diseases from the water.
Since it is not economical and practical to test for each
and every microorganism, the TC indicator tests are done
because their presence indicates the presence of pathogenic
groups of bacteria. Coliform bacteria should not be
detected in treated water supplies and, if found, suggest
inadequate treatment, post-treatment contamination, or
excessive nutrients. Thus tests for TC bacteria serves as an
indicator of both treatment efficiency and integrity of the
distributing system [5].
FC bacteria are associated with intestinal tract and
hence are released to the environment by fecal contamination
by animals as well as human fecal excreta [6]. They are
not necessarily pathogenic but their presence is indicative
of the presence of pathogenic bacteria of fecal origin.
They can enter water bodies through direct release of
waste from animals and untreated human sewage [7].
Additionally, agricultural activities like the application of
manure allow animal wastes to wash into water bodies [8].
When people consume fecally contaminated water, they
stand high chances of suffering from gastroenteric
16 Journal of Environment Pollution and Human Health
infections such as diarrhea. Children under the age of 5
years and the immunosupressed are the major victims of
diarrhea. This calls for the frequent monitoring of the
drinking water sources for their microbial quality [9]. In a
study that investigated the contamination chain of
domestic water in the Njoro Township in Kenya [10], the
E. coli (a fecal coliform) density was in the range of 0–
220CFU/100 mL (point of collection) and 0–520CFU/100
mL (low-income households and vendors). No previous
studies on water quality have been done in Mauche,
Maunarok and Kihingo locations prior to this study.
However, a study had been carried out on the fluoride
contamination of water in Lare location [11]. More studies
in Njoro location have been done on the microbial quality
of river Njoro both upstream and downstream and found a
high level of microbial contamination [9]. A different
study in Njoro Township (Njoro location) was aimed at
determining the microbial quality of drinking water
between the high income and low income households [10].
Therefore, this study is a conclusive and more informative
study on the microbial quality of drinking water in Njoro
Sub County.
Since no water quality studies have previously been
documented in Mauche, Kihingo and Maunarok locations,
this study sought to determine the overall microbial
quality of drinking water in Njoro Sub County. Previous
studies in Lare location were based on the fluoride levels
while most studies in Njoro location have mainly focused
on river Njoro. This study, therefore, sought to determine
the microbial quality of drinking water from various
sources and water stored inside various household storage
containers within the five locations in Njoro Sub-County.
2. Materials and Methods
Study area
Njoro Sub-county is located at an elevation of 1 600 to
2 000m above sea level and about 20km Southwest of
Nakuru town in the Kenyan Rift Valley Province. The
region is classified as semi-arid with a total annual rainfall
that ranges from 500mm in the lowlands to 1,800mm in
the highlands and occurring in two seasons namely the
long rains from March to April and the short rains from
October to December. The Njoro River and rain water are
the major sources of water but its volume reduces during
dry seasons. Thus other common sources of water in this
area include boreholes, wells, dams and springs. The
inconsistency in water supply in dry seasons in this area
also requires that people store water in household
containers for future use. The Sub-County is divided into
5 administrative locations namely: Njoro, Lare, Kihingo,
Maunarok and Mauche (Figure 1) with a total population
of 188,124 people. The mainstay of the economy in this
area is agri-based industries including vegetable and milk
processing, large-scale maize, wheat and barley farming
and light manufacturing industries such as timber milling,
canning, and quarrying.
Figure 1. Map of study area
Journal of Environment Pollution and Human Health 17
Sample collection
Simple random sampling was used to select the
participating villages and water was collected. The
samples were collected by visiting the homesteads at
random and taking a sample from any domestic container
that had stored water. The water from sources was
collected from any source that the researchers came across
within the 5 locations of the study area. Sterile 500mL
plastic bottles were used for sample collection. The
sample bottle was rinsed with the water sample three
times before taking the sample. Each of the samples was
replicated three times during sample collection. Water
samples from five locations of Njoro Sub-County were
collected from the river Njoro, springs, water vendor
kiosks, household storage containers, taps, wells and
boreholes. Samples were collected directly into the sample
container and transported immediately on ice to the
Egerton University Limnology laboratory for further
analysis within 6 hours of sample collection.
Improved and unimproved water sources
An improved water source is a type of water source
which as a result of a construction or intervention programs,
is protected from external sources of contamination. In
this study, the encountered and sampled improved water
sources were storage tanks, piped water/taps, boreholes,
protected wells and protected springs. Unimproved water
sources are those that are not protected in any way from
external contaminants like fecal matter. In this study, the
common unimproved water sources that were found and
sampled were river Njoro, dams, unprotected wells and
unprotected springs.
Domestic/household storage containers
These are the containers that are used to store water
inside the houses for future use in domestic settings. This
form of storage is common in areas where water supply is
not constant and hence the sources are not quite reliable.
In this study therefore, all the containers such as jerry cans,
jugs, cups, sufurias, pots and so on that were found to
having water in them were sampled three times and the
sample classified as household storage container as shown
in the results tables.
Data analysis
All the data generated during this study were coded and
entered into MS Excel 2010 and imported into
SAS version 9.1 for analysis. The means and standard
errors were determined and recorded. One way Analysis
of Variance was carried out to test whether the differences
between the means were significant or not while the
level of significance was determined using the Least
Significant Design (LSD) at α=0.05. The coliform counts
were transformed to log 10 and the results presented in
tables.
2.1. Determination of TVCC in Drinking
Water
TVCC test was done using the standard pour plate
method according to the method of [12] (Figure 2A).
Briefly, 1mL of the water sample was aseptically
transferred into clearly marked sterile Petri dishes. A
volume of 15mL of sterile molten Plate Count Agar
(PCA) at room temperature was added to each of the
Petridishes and thoroughly swirled to facilitate sample
distribution in the media. The plates were then left to
solidify at room temperature, inverted upside down and
incubated for 24 hours at 37°C. The colonies were
recorded as colony forming units per ml (CFU/1mL).
2.2. Total Coliform Counts (TC)
TC was enumerated by membrane filtration technique
method (Stuart, Bibby scientific, UK). A sterile 0.45µm,
47mm membrane filter (Sartorius, Germany) was placed
on a filter funnel. A volume of 10mL of each water
sample was added to a membrane and the vacuum pump
turned on. After the water was passed through the filter, it
was maintained in the vacuum until all liquid had passed.
The filter was then transferred using a sterile forceps to a
50mm disposable Petri dish containing Eosin Methylene
Blue (EMB) agar. Each funnel was rinsed with 20mL
distilled water between each water sample. All Petri
dishes were incubated upside down in an incubator for 24
± 2 hours at 37°C. All samples were analyzed by counting
the blue and pink colonies under a colony counter
(Acculite, Fisher, USA) and recorded as CFU/100mL as
shown in Figure2B.
Figure 2. TC (A) and TVCC (B) colonies after incubation in EMB and PCA media respectively
18 Journal of Environment Pollution and Human Health
3. Results
The samples were randomly collected leading to
unequal sample sizes among the 5 locations in the study
area. As such, during sampling, some water sources were
not found or were absent in some locations and hence not
available for sampling. Moreover, some domestic storage
containers were absent or were not found to be having any
water during sampling and they were not sampled. The
results for the sources and storage containers that were
absent or were not having any stored water are indicated
as (-) in the tables since there was no data collected for
analysis. The results obtained in this study were compared
to the WHO recommended levels for drinking water
quality as indicated in the appendices section.
3.1. TVCC in Water Sources and Water in
Various Household Storage Containers
All the sampled water sources were contaminated with
TVCC which was in the range of log10 0.48±0.12
(unprotected wells in Njoro) to 1.76±0.05 CFU/1mL (taps
in Maunarok and boreholes in Mauche) as shown in Table 1.
In the sampled household storage containers, the highest
log10 mean of TVCC CFU/1mL were recorded in buckets
used to store drinking water in Lare (2.04±0.01
CFU/100mL) while lowest means were in sufuria in
Mauche (0.48±0.09 CFU/100 mL) as indicated in Table 2.
3.2. TC Counts in Water Sources and Water
in various Household Storage Containers
All the sampled water sources in Njoro Sub-County
were contaminated with TC as shown in Table 3. The
mean log10 TC CFU/100 mL in the water sources were
highest in tanks in Mauche (2.12±0.27 CFU/100 mL) and
lowest in taps in Mauche (0.30±0.00 CFU/100 mL) and in
unprotected wells in Njoro (0.30±0.07 CFU/100mL). All
the sampled household containers were contaminated with
TC which ranged from log10 0.59±0.09 CFU/100mL (jerry
cans in Njoro) to 2.47±0.23 CFU/100mL (buckets in Lare)
as shown in Table 4.
Table 1. Mean log10TVCC CFU/1mL for water source types in Njoro Sub-County
WATER
SOURCE
KIHINGO
mean±SE
(n = number of
samples)
LARE
mean±SE
(n = number of
samples)
MAUCHE
mean±SE
(n = number of
samples)
MAUNAROK
mean±SE
(n = number
of samples)
NJORO
mean±SE
(n = number of
samples)
Unimproved sources
River - - - -
1.18±0.03a
(n=3)
Springs - - - - -
Wells - - - - 0.48±0.12
a
(n=3)
Dams - - - - -
Improved sources
Springs - - - - -
Taps/piped water -
1.14±0.18a
(n=9)
0.70±0.14a
(n=3)
1.76±0.05a
(n=3)
1.06±0.16a
(n=12)
Tanks
1.20±0.18a
(n=9)
0.63±0.15a
(n=6)
0.94±0.29a
(n=9)
1.31±0.14a
(n=15) -
Boreholes
0.69±0.14a
(n=6) -
0.48±0.13a
(n=3) - -
Wells 1.47±0.11
a
(n=6) - - - -
SE = standard error - Not tested since no sample of that type was found for collection during sampling
Means followed by the same small letter in a column are not significantly different at 5% LSD.
Table 2. Mean log10 TVCC CFU/1mL for domestic containers in Njoro Sub-County
WATER
CONTAINER
KIHINGO
mean±SE
(n = number
of samples)
LARE
mean±SE
(n = number of
samples)
MAUCHE
mean±SE
(n = number
of samples)
MAUNAROK
mean±SE
(n = number of
samples)
NJORO
mean±SE
(n = number of
samples)
Gallons
1.00±0.02
(n=3)
- - - -
Jugs - -
1.08±0.14
(n=3) - -
Cups - - - - -
Jerry cans -
1.07±0.17a
(n=6) -
1.20±0.30
(n=6)
0.93±0.08
(n=6)
Clay pots - -
1.40±0.11
(n=3)
- -
Buckets -
2.04±0.01a
(n=3)
- - -
Sufurias - -
0.48±0.09
(n=3)
- -
SE = standard error - Not tested since no sample of that type was found for collection during sampling
Means followed by the same small letter in a column are not significantly different at 5% LSD.
Journal of Environment Pollution and Human Health 19
Table 3. Mean log10 TC counts/100mL for water source types in Njoro Sub-County
WATER
SOURCE
KIHINGO
mean±SE
(n = number
of samples)
LARE
mean±SE
(n = number
of samples)
MAUCHE
mean±SE
(n = number
of samples)
MAUNAROK
mean±SE
(n = number
of samples)
NJORO
mean±SE
(n = number
of samples)
Unimproved sources
River - - - -
1.40±0.03a
(n=3)
Springs - - - - -
Wells - - - - 0.30±0.02
a
(n=3)
Dams - - - - -
Improved sources
Springs - - - - -
Taps/piped water -
1.59±0.50a
(n=9)
0.30±0.07a
(n=3)
1.64±0.49a
(n=3)
0.90±0.22a
(n=12)
Tanks
1.87±0.03a
(n=9)
1.56±0.11a
(n=6)
2.12±0.27a
(n=9)
1.73±0.13a
(n=15) -
Boreholes
1.11±0.41a
(n=6)
-
0.60±0.21a
(n=3)
- -
Wells
1.89±0.08a
(n=6)
- - - -
SE = standard error - Not tested since no sample of that type was found for collection during sampling
Means followed by the same small letter in a column are not significantly different at 5% LSD.
Table 4. Mean log10 TC CFU/100mL for domestic containers in Njoro Sub-County
WATER
CONTAINER
KIHINGO
mean±SE
(n = number of
samples)
LARE
mean±SE
(n = number of
samples)
MAUCHE
mean±SE
(n = number of
samples)
MAUNAROK
mean±SE
(n = number
of samples)
NJORO
mean±SE
(n = number
of samples)
Gallons
0.95±0.31
(n=3) - - - -
Jugs - -
2.09±0.21
(n=3) - -
Cups - - - - -
Jerry cans -
1.42±0.27a
(n=6) -
1.76±0.18
(n=6)
0.59±0.09
(n=6)
Clay pots - -
2.09±0.39
(n=3) - -
Buckets - 2.47±0.23
a
(n=3) - - -
Sufurias - - 1.74±0.08
(n=3) - -
SE = standard error - Not tested since no sample of that type was found for collection during sampling
Means followed by the same small letter in a column are not significantly different at 5% LSD.
Table 5. Mean log10 FC CFU/100mL for water source types in Njoro Sub-County
WATERSOURCE
KIHINGO
mean±SE
(n = number
of samples)
LARE
mean±SE
(n = number
of samples)
MAUCHE
mean±SE
(n = number
of samples)
MAUNAROK
mean±SE
(n = number
of samples)
NJORO
mean±SE
(n = number
of samples)
Unimproved
sources
River - - - -
0.00±0.00a
(n=1)
Springs - - - - -
Wells - - - -
0.00±0.00a
(n=3)
Dams - - - - -
Improved sources
Springs - - - - -
Taps/piped water -
1.08±0.12a
(n=9)
0.00±0.00a
(n=3)
1.43±0.05a
(n=3)
0.00±0.00a
(n=12)
Tanks
0.10±0.02b
(n=9)
0.64±0.11a
(n=6)
0.00±0.00a
(n=9)
0.97±0.28a
(n=15)
-
Boreholes
0.00±0.00b
(n=6)
-
0.00±0.00a
(n=3)
- -
Wells
1.68±0.07a
(n=6)
- - - -
SE = standard error - Not tested since no sample of that type was found for collection during sampling
Means followed by the same small letter in a column are not significantly different at 5% LSD.
20 Journal of Environment Pollution and Human Health
Table 6. Mean log10 FC CFU/100mL for domestic storage containers in Njoro Sub-County
WATER
CONTAINER
KIHINGO
mean±SE
(n = number
of samples)
LARE
mean±SE
(n = number
of samples)
MAUCHE
mean±SE
(n = number
of samples)
MAUNAROK
mean±SE
(n = number
of samples)
NJORO
mean±SE
(n = number
of samples)
Gallons
0.00±0.00
(n=3)
- - - -
Jugs - -
0.00±0.00a
(n=3)
- -
Cups
-
-
-
-
-
Jerry cans -
0.00±0.00a
(n=6)
-
0.81±0.25
(n=6)
0.00±0.00
(n=6)
Clay pots - -
0.00±0.00a
(n=3)
- -
Buckets -
0.00±0.00a
(n=3)
- - -
Sufurias - -
0.00±0.00a
(n=3)
-
SE = standard error - Not tested since no sample of that type was found for collection during sampling
Means followed by the same small letter in a column are not significantly different at 5% LSD.
3.3. FC Counts in Water Sources and Water
in Various Household Storage Containers
The mean log10 FC CFU/100mL of the sampled water
sources in Njoro Sub County is presented in Table 5
whereby the counts ranged from 0.00 to 1.68±0.07
CFU/100mL. In the sampled household containers, all the
containers had mean log10 FC counts of 0.00CFU/100mL
apart from jerry cans in Maunarok (0.81±0.25CFU/100mL)
respectively (Table 6).
4. Discussion
The results obtained for microbial quality in Njoro Sub-
county, indicated that the drinking water sources were
microbially contaminated. The high concentrations of
TVCC and TC were an indication of the load of
contamination in water otherwise meant for drinking
purposes. A similar study on microbial analysis of stored
and treated drinking water in Nakuru North Sub-county
found that 35% (189/540) of the water samples were
positive for TC (51.8%), E. coli (32.3%) and Salmonella
(15.9%) respectively [13]. This indicated that the water
from sources and storage household containers in Nakuru
North-sub-county did not meet the microbial quality
guidelines by WHO in order to qualify for drinking
purposes. Continuous changes in the water flow rate at
sources and domestic containers could be responsible for
the increased HPC due to increased microbial growth.
Based on the various tested parameters and the different
locations, there are sources and containers that were less
contaminated and hence recommended for use. However
generally, this study indicated that the clay pots, sufuria
and some jerry cans were safe for storage while the
protected wells, taps and boreholes were the
recommended sources of water since they recoded low to
no microbial counts.
The low in TVCC, TC and FC levels in household
storage containers as compared to sources was probably
due to the use of treatment methods such as boiling and
chlorination. A similar trend of decreased TC at
households was observed in a study to determine the
bacteriological quality of drinking water in Kibera slums
in Nairobi. This study found that 10% of outhouse waters
and a further deterioration of about 95% of household’s
storage containers were contaminated with fecal coliforms
[14]. On the other hand, an increase in the bacterial counts
at households as compared to the water sources might be
linked to further deterioration of drinking water with
fecally contaminated hands or objects. A study conducted
in Vietnam also found off-premises piped sources to
contain more fecal contamination than on-premises piped
sources, with evidence of similar stored water quality for
both source types [15]. Additionally, there is a possibility
of contamination of water by vendors or during
transportation from off premises to homesteads, during
storage as well as handling [10]
Microbial contamination in storage containers may be
due to lack of regular cleaning, defects on the pipe-lines or
contamination during distribution. The trends of storing
water for long in households can result to a possibility of
fecal contamination of maybe initially good-quality
drinking water. Such contamination can arise from
dipping of fecally contaminated hands or utensils in the
storage containers especially by children. This form of
contamination pathway at the household is independent of
pollution at the source because the source might be free
from contamination. These findings of this study are
similar to those of another study on the bacteriological
quality of drinking water sources in Njoro Division, which
indicated that the fecal coliform counts in the Njoro River
were higher than the WHO guidelines [10]. Another study
found that Njoro River was highly contaminated with
indicator bacteria E. coli [9]. Therefore the increased
concentration of TVCC, TC and FC is likely to result to
increased diarrheal episodes among the local communities.
The children, elderly and immunosuppressed people are
most affected from diarrhea due to low immunity. The
reports from Njoro Health Centre and Nakuru Provincial
General Hospital (NPGH) in Kenya indicate a high
prevalence of undiagnosed diarrhea which was closely
linked to consumption of pathogen-polluted waters [16].
One of the major causes of diarrheal diseases is
consumption of microbe contaminated drinking water.
These diarrheal diseases weakens the immune system
leading to higher risk of other diseases which present
themselves as opportunistic infections [12]. The results
obtained for microbial quality in Njoro Sub-County,
indicated that majority of the drinking water sources were
Journal of Environment Pollution and Human Health 21
contaminated. The high concentrations of TVCC and TC
were an indication of a load of contamination in water
otherwise meant for drinking purposes. A similar study on
microbial analysis of stored and treated drinking water in
Nakuru North Sub-County found that 35% (189/540) of
all the samples were positive for TC (51.8%), E. coli
(32.3%) and Salmonella (15.9%) respectively [13]. This
indicated that the water from sources and storage
household containers in Nakuru North-Sub-County did
not meet the microbial quality guidelines by WHO in
order to qualify for drinking purposes.
The decrease in TVCC, TC and FC levels in some
household storage containers as compared to sources was
probably due to the employment of treatment methods
such as boiling and chlorination. An increase in the
bacterial counts at households as compared to the water
sources might be linked to further deterioration of
drinking water with fecally contaminated hands or objects.
A study conducted in Vietnam also found off-premises
piped sources to contain more fecal contamination than
on-premises piped sources, with evidence of similarly
stored water quality for both source types [14].
Additionally, there is a possibility of contamination of
water by vendors or during transportation from off
premises to homesteads, during storage and handling [10].
5. Conclusion
The presence of TVCC, TC and FC in drinking water is
of great public health significance and may lead to the
onset of various enteric diseases. Being a fecal-oral
pathogen, there are other vehicles necessary for its
transmission for instance contaminated hands, foods, and
utensils. The untreated water sources and household stored
water used for drinking and other domestic purposes could
harbor other microbes which are potential threats to the
health of residents. This calls for urgent intervention
strategies by the government, the community and other
stakeholders to minimize the health risks associated with
consumption of contaminated water.
Competing Interest
The authors have no competing of interest.
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Appendix
Appendix 1: The WHO microbial quality guidelines for
drinking water.
parameter
Guideline
Total coliforms
0 CFU/100mL
Fecal coliforms
0 CFU/100mL
Total viable cell counts
Not specified