JCBPS; Section D; May 2017 – July, 2017, Vol. 7, No. 3; 603-611.
E- ISSN: 2249 –1929
[DOI: https://doi.org/10.24214/jcbps.D.7.3.60311]
Journal of Chemical, Biological and Physical Sciences
An International Peer Review E-3 Journal of Sciences
Available online atwww.jcbsc.org
Section D: Environmental Sciences
CODEN (USA): JCBPAT Research Article
Bacteriological and physicochemical quality of Jimma town
water supply at pre and post distributed to Jimma town
residents, Oromia regional state, southwestern Ethiopia
1Diriba Fufa, 1Shiferaw Demissie and 1Gadisa Natea
1
Department of Biology, Jimma University, P.O. Box 378, Jimma, Ethiopia
Received: 19 May 2017; Revised: 13 June 2017; Accepted: 26 June 2017
Abstract: Often, the quality of drinking/potable water has been a major health concern,
particularly in developing countries, where 80% of the disease cases are attributed to
inadequate sanitation and use of contaminated water. The aim of this study was to assess
the bacteriological and physicochemical quality of Jimma town water supply. During this
study, survey of sanitary programs applied by local water system supplier was conducted.
Moreover, standard microbiological methods were carried out for determination of
bacterial load and detection of coliforms, and also physicochemical analysis such as free
residual chlorine, total dissolved solids (TDS), chemical oxygen demand (COD),
turbidity and odour were conducted, accordingly. Results of this study indicated that,
the turbidity of the water at site A and B had been a ranged from 1.0 – 1.22, 15.6-16.0
NTU(nephelometric turbidity units), dissolved solids 515 – 525, 1150-1250 mg/l, total
hardness 118-134, 255-265mg/l, and free residual chlorine 0.31-0.53, 0 mg/l,
respectively. Moreover, water samples collected from site B (Jimma town, i.e. from water
pipes) were positive for coliform bacteria, which was ranged between 11-33 MPN
(CFU/100 ml). In contrast, none of coliform bacteria detected from site A (at Jimma town
water treatment plant). Generally, result of bacteriological and physicochemical study
indicated that potable water used by Jimma town residents was beyond the maximum
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Bacteriological … Shiferaw Demissie et al.
tolerable level recommended by WHO. Thus, it calls for appropriate intervention and
improving the existing methods of water treatments.
Keywords: Bacteriological, Jimma, physicochemical, potable water, treatment
INTRODUCTION
Water is very essential natural resource in the world and require for metabolic functions and homeostasis
in living cells. The human body is composed of about 60% water by weight in adult males, 50% in
females and 70% in new born infants1.The human dietary requirement for water is estimated to be
approximately two liters per day for an average adult2. The regular intake of adequate amount of water is
essential in maintenance of good health and well-being2. However, the most important attributes of
drinking water has to be assured and maintained is safety and quality3 to insure that it is safe for human
consumption.
It have been understood that potable water should be free from harmful contaminants, such as pathogenic
microorganisms, toxic substances, physical and chemical residue, undesirable organoleptic properties like
odor, color and taste3. Water borne illness could be occurring as result of water supply contamination by
biological and chemical contaminants. In 2004, a waterborne illness outbreak affected 1450 visitors and
residents in south bass island, Ohio4. In fatal water borne disease outbreak had occurred in Ontario,
Canada, in May 2000, and 2300 persons became seriously ill and seven died because of water
contamination with bacterial pathogens Escherichia coli O157:H7 and Campylobacter jejuni5.
The United Nations general assembly has been declared period 2005 to 2015 as international decades for
action, ‘Water for Life’ (WHO) 6. The UN also recently announced that “safe and clean drinking water is
human right essential to full enjoyment of life and all other human right” (WHO) 6. Hence, provision of
safe drinking water is paramount issue of health and development at Local, Nationals and International
levels.
In spite of the importance and popularity of water, they have been understood as posing a risk for
infection by some fast growing pathogenic microorganism7. Usually, water can be contaminated by
different contaminants at various points either before treatment or after treatment. This includes water at
the source of distribution and after it is distributed to the communities. Therefore, water should meet
potable water standard by being free or limited to microorganisms, transparent, odorless, and tasteless
liquid having freezing point of 0 C and boiling point of 100 C7. Thus, this study was designed to
determine the bacteriological and physicochemical quality of Jimma town water supply at pre and post
distributed to the town residents.
MATERIALS AND METHODS
Descriptions of the study area: This study was conducted at Jimma town, Oromia regional state, located
at about 353 km to southwestern of Addis Ababa, the capital city of Ethiopia. The town has an altitude of
1740 m above sea level and has latitude and longitude of 7, 39’ N and 36, 50’ E, respectively. And also
has annual minimum and maximum temperature of 13.2 and 28, respectively and with annual average
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Bacteriological … Shiferaw Demissie et al.
rainfall of 152 mm. Jimma water treatment plant provides treated water to Jimma town residents. The
treatment plant is found 5 km to the southeastern part of the town. The oldest one had been built in 1991
and produces 13,000 m3 volume of water per day, while the newly constructed in 2015 was produces
21,000 m3 water per day.
Sample collection: Stratified sampling techniques were carried out to sample water for bacteriological
and physicochemical analysis8.The sample was taken repeatedly from treated water at the source and
distributed water. A 250 ml potable water sample was collected using sterilized, non-reactive borosilicate
glass bottle.
Physicochemical characteristics of water samples: Physicochemical parameters of waters samples
including pH, turbidity, total dissolved solids, color, odor, total hardness, chemical oxygen demand,
temperature, and free residual chlorine were determined, accordingly.
pH: After stirred of about 250 ml potable water sample, it’s pH was measured using pH meter
(HANNA instrument, Portugal).
Turbidity: Turbidity was determined using the cell riser, which installed in the cell holder of model
2100A turbid meter in one of the two highest ranges (100 or 1000 NTU). A clean sample cell of turbid
meter filled with 25 ml of each sample and covered with light shield and turbidity read in nephelometric
turbidity units (NTU) 9. Moreover, the temperature and chemical oxygen demand (COD) of water sample
were measured using Thermometer and Wagtech photometer (POTALAB), respectively.
Free residual chlorine: Free residual chlorine is amount of chlorine residue left in the water after
treatment. It was analyzed using Wagtech photometer.
Total hardness and dissolved solids: The presence of total hardness in water may affect its taste (WHO)
10
. For this reason, total hardness and total dissolved solids determined by Wagtech photometer for both
sample types.
Bacteriological enumeration and analysis: From appropriate serial dilutions, 0.1 ml of the aliquot was
seeded on Plate Count Agar (PCA)11, MacConkey agar12 ,Mannitol Salt Agar (MSA)13 and incubated at
32°C for 48 h for count Aerobic mesophilic bacteria, Enteriobacteriaceae and Staphylococci, respectively.
Most probable number test for determination of coliform bacteria: MPN is the statistical multistep
lab analysis based on assumption of poison distribution of number of coliform bacterial cell present in the
water14. This was carried out using the three phases including Presumptive, Confirmed and Completed
tests as described below:-
Presumptive test for coliform bacteria: Three sets of five tubes each in a test-tube rack were arranged. The
tubes in the first set (S1) hold 10 ml of double-strength presumptive Mackonkey broth medium with
inverted Durham tubes, while the tubes in the second and third sets (S2, S3) contain 10ml of single-
strength presumptive medium with inverted Durham tubes. With a sterile pipette 10ml of water sample
was inoculate into each of the five tubes in set one (S1), 1ml of sample to each of the five tubes in set
two (S2), and 0.1ml of water sample into each of five tubes in set three (S3). All tubes had been shaken
gently to distribute the sample uniformly throughout the medium. Then, the tubes were incubated at 37°C
for 24-48 h. After incubated for 24h, each tube was examined for the presence of gas. A tube produced
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Bacteriological … Shiferaw Demissie et al.
gas considered as positive, while tube with no gas produced further incubated for 24 h. Then, number of
the positive tubes were recorded, which was produced gas either after 24 or 48 and MPN was calculated
according to MPN tables.
Confirmation test for coliform bacteria: From each presumptive positive tube (gas production), a loop
full of bacterial culture was streaked onto Eosin-methylene blue agar (EMB), and incubated at 37°C for
24h. Nucleated small colonies (dark centers) surrounded with metallic sheen considered as E. coli.
Completed test for coliform bacteria: To differentiate E. coli from Enterobacter aerogenes, Indole test
was performed. The sample from presumptive tube had been added into each tube of tryptone water.
Then, approximately 0.1 ml of Kovacs reagent was added and mixed gently. Formation of indole and gas
production indicated the presence of E. coli (APHA) 15.
Data analysis: Results are presented as mean ± SD. Percentage of coefficient variation (% CV) was
calculated to see if there was significant variation in counts within the water samples analyzed. Mean
values of water samples were compared using one way ANOVA (P < 0.05).
RESULTS
Jimma town water supply sanitation status: Overall, the Jimma town water supply manager and
workers reflexed that potable water of Jimma town was poor due to ineffectiveness of treatment plant and
deficiency of expertise (Table 1).
Table 1: Key sanitation elements implemented at Jimma town potable water supplier
Sanitation program elements At Jimma town water supplier plant
Physicochemical parameters Coagulation, Sedimentation, Filtration,
Disinfection(chlorination) were performed
Bacteriological parameters monitored None
Water sources Seka Gibe River
Physicochemical characteristics of Jimma town potable water: Results of physicochemical
characteristics indicated that turbidity 15.80, 1.02 NTU, total hardness 255-265, 118-134 mg/l, and
chemical oxygen demand 16-18, 8-10 ppm were recorded from site B and A, respectively. Moreover, in
both site (A and B) colourless and odourless water sample was observed (Table 2).
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Table 2: Physicochemical characteristics of potable water, Jimma town, 2017
Parameters Mean values of water physicochemical characteristics
Site “A” Site “B” WHO standard National standard
pH 7.01 0.9 6.4 2 6.5-8 6.5-8.5
Color(TCU) 5 6 5-50 5-50
Odor unobjectionable unobjectionable unobjectionable Unobjectionable
Temperature (C ) 20 2 28 2 - -
Turbidity(NTU) 1.02 0.2 15.80 <5 <5
Chemical oxygen demand (ppm) 82 16 2 10 < 12
Total hardness as CaCO3 (mg/l) 126 8 260 5 100-500 100-600
Free residual chlorine(mg/l) 0.510.2 0 0.2-0.5 0.2-0.6
Total dissolved solids(mg/l) 520 5 1200 50 < 1000 500-1500
Note:- Site “A” represents water sample taken from Jimma town water treatment plant,while site “B”
water taken from Jimma town (water pipes). Values represent means from the three replicates ±
standard deviation.
Bacteriological analysis of water samples: The result of this study indicated highest mean count of
aerobic mesophilic bacteria (3.17 log CFUg-1) and Enterobacteriaceae (2.04 log CFUg-1) were
recorded from site B. However, others microbial group such as Staphylococci and spore former
bacteria were not detected from the both sites (Table 3).
Table 3: Mean of microbial counts (log CFUg-1) from water treatment plant and pipes
Sample source Microbial mean counts ( log CFUg-1 ± SD)
AMB Entero Staph
Site A 1.02 + 0.03 - -
Site B 3.17+ 0.2 2.04 + 0.05 -
Where: AMB = Aerobic mesophilic bacteria, Entero = Enterobacteriaceae, Staph, Staphylococci, SD=
Standard deviation, CFU= Colony forming unit.
Determination of coliform bacteria: The result of MPN has shown that none of coliform bacteria
were detected from Site A (at water treatment plant) (Table 4), while at site B (from water pipes),
among a total of 12 water samples had been examined, 9 water samples were positive for coliform
bacteria, in which growth of bacteria, gas and acid production were observed (Table 5). Furthermore,
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Bacteriological … … Shiferaw Demissie et al.
nucleated small colonies" (dark centers) with metallic sheen were indicated onto EMB agar, and also
indole and gas production in Tryptophan medium was showed.
Table 4: Values of MPN per 100 ml of water sample (10, 1, 0.1ml test portion were used) at Jimma
town water treatment plant (at source of distribution)
No. of tubes giving positive reaction MPN ( per 100ml) 95% confidence
at treatment site limits
Sampling 5 of 10ml 5 of 1ml 5 of 0.1ml Lower Upper
Time
Morning S1 0 0 0 <2 0 5.9
S2 0 0 0 <2 0 5.9
S3 0 0 0 <2 0 5.9
Evening S1 0 0 0 <2 0 5.9
S2 0 0 0 <2 0 5.9
S3 0 0 0 <2 0 5.9
Where: S- stand for sample.
Table 5: Values of MPN per 100 ml of water sample (10, 1, 0.1ml test portion are used) for water
sample at Jimma town (From water pipes)
No. of tubes giving positive reaction at Jimma MPN ( per 100ml) 95% confidence
town (after distributed for residents) limits
Sampling 5 of 10ml 5 of 1ml 5 of 0.1ml Lower Upper
Time
Morning S1 4 2 0 22 6.8 67
S2 4 3 1 33 11 90
S3 3 2 1 17 5 46
Evening S1 3 2 1 17 5 46
S2 3 1 1 14 4 34
S3 3 1 0 11 2 25
DISCUSSION
Drinking water is a live, not sterile by its nature. It have been realized that potable water should be
free of biological and chemical contaminants. Thus, both its physicochemical and bacteriological
standard should meet WHO standard. In the current study, the physicochemical and bacteriological
qualities of Jimma town potable water at the treatment plant and after it is distributed was assessed.
The study was targeted to compare bacteriological and physicochemical quality at the treatment site
and after it is distributed for consumers with WHO standard and Ethiopian drinking water standard
(National standard).
Often, the water is collected from the source (Seka Gibe River) using pump, and treated. Thereafter, it
is distributed to residents through pipes lines. In terms of water treatment and disinfection, the
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methods employed were coagulation by addition of aluminum sulfate, filtration and chlorination. In
both cases at treatment plant as well as in pipes, bacteriological monitoring was not applied, which
may be due to deficiency of resources (materials), and bacteriological techniques. Thus, potable water
of Jimma town could be exposed to human pathogenic microorganisms. As a result, it is difficult
whether it’s safe for drink or not as a context of biological quality. In addition there was also no
inspection of the pipe from time to time, which might be seep slowly into underground water pipe,
thereby polluting it.
Furthermore, long lasting usage of water from Seka Gibe River may lead to deterioration of the water
quality, because the pipeline may become corroded with random cracks and in most cases clogged
with sediment16. This could allow the passage of inorganic metals and bacteria. The founding of this
study directing that there is a the possibility of the presence of pathogens that may cause acute
intestinal illness, which are generally considered discomfort to health, particularly to
immunocompromised groups (such as infants, pregnant, elderly and those who are sick) 17.
The result of physicochemical analysis of water showed that the pH of the water samples taken from
Jimma town (site B) couldn’t accordance with standard requirements. Their values are less than the
lower limits of the pH (6.5) recommended by WHO, which determine the physicochemical
characteristics of waters 18.
Total dissolved solids (TDS) is used to describe the inorganic salt and small amount of organic matter
present in water, which its presence may affect the taste water9 (WHO, 1996). Although in the current
study the TDS of Jimma town potable water within the range of National standard, it was inflated
beyond the WHO standard, which has been shown from 1150- 1250mg/l. It has been indicated that
drinking water with extremely low concentration of TDS may be unacceptable because of its flat
insipid taste10. Moreover, its turbidity was not with WHO and National standard. Water turbidity is
very important because high turbidity is often associated with higher level of toxic chemical, heavy
metals and disease causing microorganism and parasites19. All the water samples analyzed in this
study have unobjectionable odor and color which is in agreement with the standard color of 6 TCU
and 5TCU by WHO (WHO) 20.
In the present study, the mean total counts of AMB (3.17 CFUg-1), and Enterobacteriaceae
(3.17 CFUg-1) were observed from water sample taken from pipes, while insignificant amount of
bacterial load detected from treatment plants. The increment of these bacteria load at site B could be
because of the leakage and getting old water pipes, which is greater than earlier result of drinking
water of India21. But, lower than the earlier report from Awetu River cross the Jimma town22, as they
indicated AMB 4.1-6.8, and Enterobacteriaceae 3.91-5.59 log CFUg-1 .
The coliform counts of water taken from Jimma town (site “B”) were generally not fit (i.e.11- 33MPN
(CFU/100 ml) with that of WHO and National standards of drinking water. It have been exceeded the
standard requirement of 10 coliforms count per 100 ml for national standard and zero coliform count
per 100 ml for WHO (WHO, 2002)23. High coliform counts indicate that the potable water of Jimma
town could be fecal contaminated, which also a risk for pathogenic microorganisms (i.e. Salmonella,
Campylobacter spp.) and parasitic organism such as Giardia and Cryptosporidium may be present19.
Thus, it needs regularly treatment and inspection.
Nevertheless, water samples taken from treatment plant (site “A”) were negative for coliforms. This
indicated that, the water at treatment plants safe from microbial as well as its physicochemical
contaminants. But, after it was distributed into Jimma town its physicochemical and bacteriological
qualities were deviated from the normal standard recommended by WHO and National standard of
drinking water. This was due to the fact that there were no proper and adequate inspections of the
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Bacteriological … … Shiferaw Demissie et al.
water pipe lines as well as the distribution system regularly starting from the treatment plant to the
consumers end.
On the other hand in this study, no E. coli were detected from site ‘A’ (at treatment plant), which
indicates that all the water samples are free from faecal contamination. However, the water sample
taken from Jimma town has been shown E.coli. Undoubtly, detection of coliform bacteria and
physicochemical characteristics of potable water is a crucial because of the determinant indicator of
faecal, pathogenic microorganisms and toxic chemicals/elements contamination of drinking water that
greatly danger for public health. In conclude, the physicochemical and bacteriological value of Jimma
town pipe water is beyond the maximum tolerable limits recommended by WHO standards. Thus, it
needs immediate inspection by concerned body.
ACKNOWLEDGEMENTS
The Jimma University (https://www.ju.edu.et) is gratefully acknowledged for provided research
facilities, as well as academic supports for the first author.
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* Corresponding author: Shiferaw Demissie,
Department of Biology, Jimma University, P.O. Box 378, Jimma, Ethiopia
On line publication Date: 26.06.2017
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