UMYU Scientifica

A periodical of the Faculty of Natural and Applied Sciences, UMYU, Katsina

ISSN: 2955 – 1145 (print); 2955 – 1153 (online)

ORIGINAL RESEARCH ARTICLE

Microbiological and Physicochemical Quality of Influent and Treated Tap Water in Sokoto Metropolis: Evidence of Post-Treatment Contamination

¹Salisu, H., ¹Muhammad, U.K., ¹Manga, S.B., ²Shamsudeen, S., ³Hayatu, N. G And ⁴Bello B.Y

¹Department of Microbiology, Faculty of Chemical and Life Sciences, Usmanu Danfodiyo University, Sokoto

²Department of Microbiology, Faculty of Life Sciences, Bayero University, Kano

³Department of Soil Science and Land Resources Management, Faculty of Agriculture, Usmanu Danfodiyo University, Sokoto.

⁴ Department of Biology, College of Advanced Studies and Technology, Sokoto.

Corresponding author: hussaininahuche@gmail.com

ABSTRACT

This study examines the microbiological and physico-chemical properties of influent and treated water sources for municipal use in Sokoto Metropolis, Nigeria. Water samples were collected from Sokoto Mechanic Village, Tudun Wada, Waziri Ward C, Tashar Illela Garage, Sokoto Water Board, Nakasari, Mabera, Tsohuwar Kasuwa, Minanata, and Runjin Sambo areas, then analyzed for temperature, pH, turbidity, total dissolved solids, hardness, biological oxygen demand, bicarbonate, electrical conductivity, dissolved oxygen, and heavy metal concentrations. Microbiological assessments included coliform tests and total bacterial counts of isolated bacterial species. The results showed variations in water quality across sampling locations, with some sources exceeding World Health Organization (WHO) and National Standard Drinking Water Quality (NSDWQ) standards for drinking water. High levels of coliforms and the presence of antibiotic-resistant bacteria in influent and treated water highlight potential public health risks. Despite treatment efforts, some areas still exhibited microbial contamination, underscoring the need for improved water treatment protocols. S. marcescens was isolated at Sokoto Mechanic Village and Tashar Illela Garage; E. coli was found at Tudun Wada and Runjin Sambo; S. aureus at Waziri Ward C; V. cholerae at Sokoto Water Board; K. pneumoniae at Nakasari; S. typhi at Mabera; Enterobacter sp. at Tsohuwar Kasuwa; and C. freundii at Minanata. This study highlights the importance of continuous monitoring and enhanced treatment strategies to ensure the availability of safe drinking water for the growing population of Sokoto Metropolis.

Keywords: Water quality, microbiological assessment, physico-chemical analysis, Sokoto Metropolis, bacteria species.

INTRODUCTION

Almost every living organism needs water either directly or indirectly for its survival. Over 70% of the Earth's surface is covered with water. This is the reason why water is the most abundant naturally occurring chemical substance found on the Earth's crust (Mathew & Krishnamurthy, 2017). It is estimated that about ninety-seven percent (97%) of the Earth's population depends on water for survival (Mathew & Krishnamurthy, 2017), while food production heavily depends on water; as such, the minimum standard of quality treatment is required (Mathew & Krishnamurthy, 2017). The quality of water is determined by its physical, chemical, and biological properties. Therefore, water quality should be evaluated before use. Consequently, the most relevant quality parameters that could affect water quality should be assessed (Shah, 2017). Despite advances in water treatment technologies, many communities (such as the study area) struggle to access enough, clean, and safe potable water, leading to a range of health problems and economic burdens (Walker et al., 2012).

Only recently has the environment been recognized for its role in the global spread of antibiotic resistance related to clinical use. Aquatic environments, specifically, may receive water from urban sewage and runoff from agricultural facilities. The occurrence of antibiotic resistance in aquatic environments has been reported since the 1970s, when Enterobacteriaceae were observed in rivers in the USA (Feary et al., 1972). Furthermore, it has been demonstrated that rivers and lakes that are contaminated with wastewater effluent also contain ARBs (Iwane et al., 2001; Czekalski et al., 2012). Antimicrobial-resistant microorganisms in water may originate from waste, including human and animal faeces (Burgmann et al., 2018). This is generally due to the fact that the microbes from these organisms had, at some stage, been exposed to antibiotics, either for therapeutic purposes (infection control or as a prophylactic) or as growth promoters in the case of animal-rearing practices (Burgmann et al., 2018).

Heavy metals contamination in earth dam water bodies also poses significant environmental and public health challenges (Manhas, 2025; Tazri et al., 2025). Heavy metals, such as lead (Pb), mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), and nickel (Ni), can enter water bodies through natural geological processes or human activities like industrial discharge, mining, agricultural runoff, and improper waste disposal (Chen et al., 2025; Sultana et al., 2025). Once these metals are introduced into an earth dam, they often remain in the ecosystem because of their non-biodegradable nature (Chen et al., 2025). This persistence leads to the accumulation of heavy metals in sediments, water, and aquatic organisms, resulting in long-term environmental damage and posing risks to both human and ecological health (Datta et al., 2025). Heavy metal contamination is a major global ecological concern; it frequently contaminates soil, sediments, and wastewater, where it stays persistent and becomes toxic to many species once it exceeds certain threshold levels (Bilyaminu et al., 2025). Only recently has the environment been recognized for its role in the global spread of antibiotic resistance related to clinical use. Aquatic environments, in particular, may receive water from urban sewage and runoff from agricultural facilities. The presence of antibiotic resistance in aquatic environments has been reported since the 1970s, when Enterobacteriaceae were observed in rivers in the USA (Feary et al., 1972). Furthermore, it has been shown that rivers and lakes contaminated with wastewater effluent also contain ARBs (Iwane et al., 2001; Czekalski et al., 2012). Antimicrobial-resistant microorganisms in water may originate from waste, including human and animal feces (Burgmann et al., 2018). This is generally because microbes from these sources had, at some point, been exposed to antibiotics—either for therapeutic purposes (infection control or prophylaxis) or as growth promoters in animal-rearing practices (Burgmann et al., 2018).

MATERIALS AND METHODS

Study Area

Sokoto State is situated in the North-western part of Nigeria. The State lies between longitudes 5.136040 E to 5.302310 E and latitudes 12.956610 N to 13.083790 N. Shares boundaries with the Niger Republic to the North, Kebbi State to the South, Zamfara State to the East, and the Benin Republic to the West. The normal annual rainfall is about 640mm, with the rainy season lasting between May and October, and the dry season extending between November and April. The temperature is as high as 43°C around March/April (middle of the dry season) and as low as 23°C in December/January (middle of the cold season). The Sokoto town area is drained by the westward-flowing Sokoto-Rima River system, which is responsible for rich alluvial soil suitable for a multitude of crops. The valley has a usual altitude of 240 meters above sea level, representing the lowest level in the study area. The highest part of the study area has an altitude of about 321 meters above sea level, giving an altitudinal difference of 81 meters. The metropolis has an estimated population of 685000 persons spread over a geographical area of 31041 km² (National Population Commission, 2022).

Figure 3.1: Showing the Map of the study area. (Source; GIS) Geography Department

Water Sample Collection.

All samples were collected for a period of five months between January to May, 2025. A total of 30 water samples were collected from ten (10) different locations, each sample was collected in triplicate, these include: Sokoto Mechanic Village, Tudun Wada Point, Waziri Ward C Point. Tashar Illela Garage Point Sokoto Water Board, Nakasari Area, Mabera, Tsohuwar Kasuwa, Minanata, and Runjin Sambo areas, respectively. The Samples were collected in sterile sample collection bottles from the study areas, 500ml from each water point, sealed, and labeled appropriately. The samples were immediately transported in a cooler with ice packs to the Microbiology laboratory and Agric chemical laboratory for initial processing (Lazarus, 2008).

Physico-chemical Analysis of Water Samples

Measurement of Temperature

This was carried out by using a mercury-in-glass thermometer.

Determination of pH

The pH of the water was determined using pH meter. 10 ml of each of the samples was poured into a sterile beaker, and the anode of the pH meter was dipped into it, and the readings were obtained (Burgmann et al., 2018).

Turbidity

The joined tube was held over a white paper, while slowly pouring the water sample into the tube until the black cross at the bottom was no longer visible. At this point, the reading was taken from the site of the tube, as the turbidity value of the water sample.

Turbidity was measured by using a 2100 turbidity meter (Burgmann et al., 2018).

Determination of Bicarbonate

Twenty-five milliliters (25 ml) of the water sample were measured into a conical flask, and a few drops of phenolphthalein indicator were added to the water sample. The pink coloration indicated the presence of carbonates (EA., 2012).

Calcium and Magnesium

Inductively coupled plasma-Atomic Emission Spectroscopy (ICP-ES) was used to determined mineral components. The unit of measurement is mg/ℓ (Apha, 2015).

Chloride

Ion chromatography (Metrohm 761 Compact IC-system A) Verification standards were run after every 10th sample (Apha, 2015).

Biological Oxygen Demand (BOD)

Three hundred 300ml of BOD bottles with 10ml of water sample were incubated at 20 °C for five (5) days, and the bottles were sealed without air bubbles, followed by measuring the difference in oxygen content before and after incubation. Then, day five 5 reading was subtracted from day one (1) reading to determine the BOD level (Lechevallier et. al., 2023).

Dissolved Oxygen Demand (DOD)

Ten (10) ml of Manganous sulphate solution was added to 50ml of the water sample using a pipette, along with five (5)ml of alkali-iodide reagent. The solution was kept for 2 min to allow the reaction to dissolve. After the precipitates were formed, two (2) ml of sulphuric acid was added to dissolve the precipitate. Then titrated with sodium thiosulfate solution using starch indicator till the blue hue fades (Lechevallier and Kwok-keung., 2018).

Total Dissolved Solids (TDS)

The water sample is filtered and the filtrate evaporated in a tarred dish on a steam bath. The residue after evaporation is dried to constant mass at 103-105°C or 179-181°C.

Bacteriological Analysis

Coliform Test

Presumptive Test

The first set of three tubes contained 10ml of sterile Double Strength Lactose Broth (DSLB), and Durham tubes were inserted before sterilization. In each of the tubes, 10 mL of water samples was added using sterile pipettes. Similarly, 1 ml of water to 3 tubes containing 10ml of single-strength medium and 0.1ml of water to the remaining 3 tubes containing 10 ml of single-strength medium were incubated at 37 °C for 24-48 hours. The presence of faecal coliforms was observed, and gas production was also observed. Acid production was determined by colour change in all the tubes from reddish purple to yellow, and gas production was determined by the entrapment of gas in the Durham tubes (Eckner, 2022).

Confirmed Test for Coliforms

Confirmed test was carried out by transferring a loopful of culture from a positive tube from the presumptive test into a tube of sterile Brilliant Green Lactose Bile (BGLB) and incubating at 37 °C for 24-48 hours. Gas production and total coliforms were observed (Adetunde and Glover, 2010).

Completed Test for Coliforms

A complete test for coliforms was carried out by streaking a loopful of broth from a confirmed test onto Eosine methylene Blue (EMB) agar plates. The plates were incubated at 37 °C for 24-48 hours. Colonies were observed on EMB agar, which were identified as faecal coliforms. Colonies with green metallic sheen were confirmed to be faecal coliform bacteria (Adetunde and Glover, 2010).

Isolation and enumeration of Bacteria

Spread plate method. A hundred microliter (100 μl) of each dilution factor 4 and 5 of the samples were inoculated into already prepared sterile nutrient agar, Eosine methylene blue agar, and MacConkey agar plates. The inocula were spread evenly with a sterile spreader, left on the bench for 30 minutes to diffuse, inverted, and incubated at 37 °C for 24 hours and 42 °C for 24-42 hours for fecal coliforms on MacConkey agar. The Most Probable Number (MPN) method was employed using multiple-tube fermentation, and a presumptive test for coliform bacteria was performed on MacConkey broth. After incubation at 37°C for 48 hours, the tubes with acid and gas were considered positive for coliforms. Positive tubes from MPN were determined following the standard probability table as described by Dhawale and LaMaster (2003). In addition, the presence of Escherichia coli was confirmed by streaking a loopful of broth onto Eosine Methylene Blue (EMB) agar and evaluating for the formation of metallic green sheen colour, a positive test for the presence of E. coli (Adetunde and Glover, 2010).

Identification and characterization of bacterial isolates.

Viable counts of the bacteria were determined after incubation. Distinct colonies from each nutrient agar, Thiosulfate-citrate-bile salts-sucrose agar, Eosine methylene blue agar, and MacConkey agar plates were counted and recorded in CFU/ml. Discrete colonies were picked for subculturing onto prepared agar plates aseptically to get distinct colonies and stocked in agar slants for further experiments. Isolates were presumptively identified based on cultural (shape, color, opacity, elevation, colony size), morphological Gram staining test, and biochemical tests i. e catalase, oxidase, citrate utilization test, indole, sugar fermentation, and triple sugar iron tests (Manga and Oyeleke, 2008).

RESULTS AND DISCUSSION

Table 1: Relative weight of Physicochemical Parameters of Water Board after treatment compared with Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 84.66

Table 2: Relative weight of Physicochemical Parameters of Minanata area Compared with Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 98.21

Table 3: Relative weight of Physicochemical Parameters of Tsohuwar Kasuwa area, Sokoto, Compared with Standard Water Quality Index

Table 4: Relative weight of Physicochemical Parameters of Runjin Sambo area Sokoto, Compared with the Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 93.2

Table 5: Relative weight of Physicochemical Parameters of Mabera area Sokoto Compared with Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 104.5

Table 6: Relative weight of Physicochemical Parameters of Water Board before treatment compared with the Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 139

Table 7: Relative weight of Physicochemical Parameters of Mechanic Village Compared with Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 371.52

Table 8: Relative weight of Physicochemical Parameters of Waziri Ward C area, Sokoto, Compared with Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 611.32

Table 9: Relative weight of Physicochemical Parameters of Tudun Wada area Sokoto, Compared with the Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 189

Table 10: Relative weight of Physicochemical Parameters of Tashar Illela Garage area Sokoto Compared with Standard Water Quality Index

WQI = \(\sum_{\mathbf{i}}^{\mathbf{n}}{= \mathbf{Wi}}\) ⁼ 189

Table 11: Water Quality Classification based on WQI value

Table 12: Presents the Statistical Analysis of Effluent and Treated Water Sources in Sokoto Municipal by using pair t- test.

Keys: TEM: Temperature, EC: Exchangeable catch ions, TDS: Total Dissolved Solid, BOD: Biological Oxygen Demand, DO: Dissolved Oxygen and SD: Significant Difference among the Variable.

Noted: Significant differences are said to be exist when the calculated t value is greater than the tabular value at the degree of freedom at ≤ 0.5% confidence limit

Table 13: Most Probable Number (MPN) Analysis of the Influent Water Samples

(CLSI, 2022)

Table 14: Most Probable Number (MPN) Analysis of the Treated Water Samples

(CLSI, 2022)

Table 15: Biochemical characteristics of Bacteria Isolated from water Samples

Figure 4.1: Representation of Frequency and Percentage of Occurrence of Bacteria Isolated from Influent Water Sample

Biochemical characteristic of Bacteria Isolated from Treated water Samples

Key: Cit=Citrate, Ur=Urase, Cat= Catalase, In=Indole, Mot=Mortality, Glu=Glucose, Suc= Sucrose, Lac=Lactose, Coa=Coagulase, MB=Mabera, MNN=Minannata and TK=Tsohuwar Kasuwa.

DISCUSSION

Table 1 Show the physico-chemical parameters conducted in this study namely; color, taste, ordor, temperature (27.7-31.7⁰C), alkalinity (15-100mg/1), pH (0.16-8.0), total hardness (1.0-100gm/1), calcium (1.0-36mg/1), magnesium (2.0-57mg/1), chloride (00.2-0.5mg/1), total dissolve solid (1.00-120mg/1), total suspended solid (nil), turbidity (1.00-7.0mg/1), nitrate (0.4-24.00mg/1), copper (0.00-0.10), chromium (0.00-0.06), lead (nil), biological oxygen demand (16.00-39.0mg/1), dissolved oxygen (7.00-13.00mg/1), bicarbonate (0.01-12.00mg/1) and exchangeable actions (.00-17.00mg/1). It could be deduced that the water samples were high in total dissolved solids, biological oxygen demand, magnesium, total hardness, alkalinity, and temperature, while chromium and copper were observed to be low. However, this study is similar to the work of Idehen, 2020 and Singh et .al., 2019, report the following physico-chemical parameters; hardness (32-114mg/1), calcium (18.0-59.0mg/1), magnesium (18.0-57.0mg/1), chloride (32.0-48.0mg/1), total dissolved solid (60.0-130), alkalinity (17.9-59.0), nitrate (0.15-0.30mg/1), pH (5.15-7.23), temperature (26.2-29.2), turbidity (4.00-7.00) and conductivity (38.7-84.5 ℳs/cm) from wells situated in Ille-Oluji popularly known for cocoa plantation. Similarly, this study is different from the report of Yasin et al., 2015 and Sesugh et al., 2019, report the physico-chemical parameters from shallow wells around cement factories which also a vital point of water contamination in the society; turbidity (17.5-51.5), pH (4.10-5.0), total dissolved solid (270-959mg/1), total suspended solid (53.0-70.0mg/1), conductivity (4.30-893 ℳs/cm), irons (0.25-1.16mg/1), manganese (0.33-0.92mg/1), zinc (0.075-0.127) and no activity was recorded on biological oxygen demand, temperature and copper.

The results in Table 2 revealed that Sokoto Water Board, Minanata, and Runjin Sambo had good water for drinking based on the water quality index (WQI) rating. In contrast, the Tsohuwar Kasuwa, Mabera, and Nakasari areas were rated to have poor water quality. Finally, Waziri C, Tudun Wada, Tashar Illela, and Sokoto Mechanic Village were unsuitable for drinking based on the water quality index, which could be a result of the very old pipe system. Most of the pipes are in poor condition. There are leakages and breakages through which contaminants from outside the pipe might enter and mix with the supplied water, or due to a lack of adequate water, these pipes often lose pressure. Moreover, due to the inadequate layout of water supply lines, there may be crossing between them. This may cause fecal contamination. Thus, it is very much possible that even if there is water, upon entering the pipes, it might no longer be suitable for drinking and pose a public health threat to the end users.

The total bacterial count, total coliform count, and total fecal count obtained from this research ranged from 10.2×10^-8 -1.5×10^-9 CFU/ml, 8.2 ×10^-4-1.5×10⁵CFU/ml, and 7.2×10⁴-2.6×10^-4 CFU/ml, respectively, which is higher than that up Yasin et al., 2015 and Sesugh et al., 2019 that report on Enterobacteriaceae isolated in well water ranged from 2.79×10⁸-9.66×10⁸CFU/ml.

Based on this study Twenty Seven (27) bacterial species were isolated namely; E. coli (5), S. marcescens (3), S. aureus (5), K. pneumoniae (1) S. typhi (2) Shigella (1) Enterobacter sp (2) V. cholerae (5) and C. freundii (3) which is in line with the work of Adebawore et.al., 2016 documented the species of bacteria isolated from necrosols collected from urban cemeteries in Poland to be: B. cereus, B. megaterium, Enterococcus faecalis, Escherichia coli, Serratia megaterium, Staphylococcus epidermidis and coagulase negative staphylococci (CNS). This is in line with some of the bacterial organisms isolated in this work. Previous reports also documented the isolation of similar organisms from water sources situated close to grave sites. Rodrigues and Pacheco (2010) and Kutlu et al. (2015) also documented the isolation of E. coli, Enterococcus sp., Staphylococcus sp., and Glycomyces sp. from funeral decomposed artifacts such as jewelry, metal dental fillings, and caskets. In addition, Adesakin et al. (2020) predominantly identified Enterobacteriaceae such as: Pseudomonas sp., E. coli, Enterococcus sp, Vibrio sp, and Bacillus sp. in domestic water samples situated close to burial grounds. This is in line with some of the organisms isolated from this study. These pathogenic organisms are associated with the gut and skin microbiome, which can consequently be released into the environment through the decomposition of humans or animals.

The presence of pathogenic bacteria such as Escherichia coli, Serratia marcescens, Staphylococcus aureus, Klebsiella pneumoniae, Salmonella typhi, Vibrio cholerae, Citrobacter freundii, and Enterobacter sp. in both influent and, alarmingly, some treated water samples indicates a serious public health risk. These organisms are known etiological agents of gastrointestinal and waterborne diseases. Their presence in treated water suggests potential post-treatment contamination or inadequate disinfection protocols.

CONCLUSION

Out of 30 water samples collected, physicochemical properties were determined from each water sample and yielded a significant result. This represents a total relative weight of each water sample; water board after treatment 84.66%, Minanata area 98.21%, Tsohuwar Kasuwa 102.07%, Runjin Sambo 93.2%, Mabera 104.5%, Sokoto water board before treatment 139%, Sokoto mechanic village 371.52%, Waziri ward C 611.32%, Tudun wada 189% and Tashar Illela Garage 139% respectively. From the result of the coliform count sample TWA of the effluent water source indicates the highest number of coliforms with MPN 2400/100ml, and WBC has the least number of coliform with MPN 3/100ml. Similarly, the sample MBA of the treated water source has the highest number of coliform with MPN 75/100ml, and sample MNN has the lowest number of coliform with MPN 7/100ml. Based on the analysis of the drinking water sources available in Sokoto communities, the coliform counts, as evident from the analysis, revealed a gross population exceeding the World Health Organization standard of 10 coliforms per 100ml of water. However, from the result of biochemical identification of both effluent and treated water sources, 27 bacterial isolates were identified from the effluent water. The name and frequency of occurrence are; E. coli 5(18.5%), S. aureus 5(18.5%), S. marcescens 3(11.1%), K. pneumoniae 1(3.7%), S. typhi 2(7.4%), Enterobacter sp 2(7.4%), Shigella flexineri 1(3.7%), P. aeruginosa 5(18.5%), C. freundii 3(11.1%) and 16 bacterial isolates were identified from treated water, the name and frequency of occurrence are; E. coli 4(24%), S. aureus 3(18.7%), S. typhi 3(18.7%), Shigella flexineri 1(6.25%), Bacillus sp 2(12.5%), Proteus sp 1(6.25%) and P. aeruginosa 2(12.5%).

REFERENCE

Achour, S., & Chabbi, F. (2014). Disinfection of drinking water. Constraints and optimization perspectives in Algeria. Larhyss Journal, 19, 193–212.

Adebawore, A. A., Awokunmi, E. E., Akinyeye, R. O., & Olanipekun, E. O. (2016). Physicochemical and bacteriological assessment of hand-dug well water from Ile-Oluji, Nigeria. American Journal of Innovative Research and Applied Sciences, 3(1), 433–440.

Adesakin, T. A., Oyewale, A. T., Bayero, U., Mohammed, A. N., Aduwo, I. A., & Ahmed, P. Z. (2020). Assessment of bacteriological quality and physicochemical parameters of domestic water sources in Samaru community, Zaria, Northwest Nigeria. Heliyon, 6(8), e04773. [Crossref]

Adetunde, L. A., & Glover, R. L. K. (2010). Bacteriological quality of borehole water used by students’ of University for Development Studies, Navrongo Campus in Upper-East Region of Ghana. Current Research Journal of Biological Sciences, 2(6), 361–364.

Adlard, C., Amri, K., & Ben, G. (1998). A DNA-based demonstration of a three-host life cycle for the Bivesiculidae. International Journal for Parasitology, 29(3), 1–5.

American Public Health Association (APHA) (2015). Standard Methods for the Examination of water and Wastewater. 21st ed. American Public Health Association, Washington DC, 12-20.

American Public Health Association. (1995). Standard methods for the examination of water and wastewater (19th ed.).

Amic, A., & Tadic, L. (2018). Analysis of basic physico-chemical parameters, nutrients and heavy metals content in surface water of small catchment area of Karasica and Vucica Rivers, Croatia. Environment, 5(4), 47–52. [Crossref]

Aminov, R. I., & Mackie, R. I. (2007). Evolution and ecology of antibiotic resistance genes. FEMS Microbiology Letters, 271(2), 147–161. [Crossref]

Anthonj, C., Diekkrüger, B., Borgemeister, C., & Kistemann, T. (2019). Health risk perceptions and local knowledge of water-related infectious disease exposure among Kenyan wetland communities. International Journal of Hygiene and Environmental Health, 222(1), 34–48. [Crossref]

Apostol, G., Kouchi, R., & Constantinescu, I. (2011). Optimization of coagulation-flocculation process with aluminum sulfate based on response surface methodology. Scientific Bulletin-University Politehnica of Bucharest, 73(2), 1454–2331.

Armstrong, J. L., Calomiris, J. J., & Seidler, R. J. (1982). Selection of antibiotic-resistant standard plate count bacteria during water treatment. Applied and Environmental Microbiology, 44(2), 308–316. [Crossref]

Bilyaminu, I. A., Shuaibu, S., Yahaya, S., Lawal, N., & Mudassiru, S. (2025). Isolation and assessment of metal tolerant bacteria and their potential for heavy metal removal. UMYU Scientifica, 4(1), 416–437. [Crossref]

Bolton, J. R., & Cotton, C. A. (2008). The ultraviolet disinfection handbook. American Water Works Association.

Bouki, C., Venieri, D., & Diamadopoulos, E. (2013). Detection and fate of antibiotic resistant bacteria in wastewater treatment plants: A review. Ecotoxicology and Environmental Safety, 91, 1–9. [Crossref]

Brazos, B. J., & O’Connor, J. T. (1985). Development of new methodology for the assessment of water treatment plant performance with respect to the removal of cyst-sized particles (pp. 345–350).

Bremere, I., Kennedy, M., Stikker, A., & Schipper, J. (2001). How water scarcity will affect the growth in the desalination market in the coming 25 years. Desalination, 138(1–3), 7–15. [Crossref]

Brüssow, H., Canchaya, C., & Hardt, W. D. (2004). Phages and the evolution of bacterial pathogens: from genomic rearrangements to lysogenic conversion. Microbiology and Molecular Biology Reviews, 68(3), 560–602. [Crossref]

Burgmann, H., Frigon, D., Gaze, W., Manaia, C., Pruden, A., Singer, A., Smets, B., & Zhang, T. (2018). Water and sanitation: An essential battlefront in the war on antimicrobial resistance. FEMS Microbiology Ecology, 94(9), fiy101. [Crossref]

Chatterjee, R., Sinha, S., & Aggarwal, S. (2012). Studies on susceptibility and resistance patterns of various E. coli isolated from different water samples against clinically significant antibiotics. International Journal of Bioassays, 1(5), 156–161.

Cheesebrough, M. (2006). District laboratory practice in tropical countries (2nd ed.). Cambridge University Press. [Crossref]

Chen, X., Ren, Y., Li, C., Shang, Y., Ji, R., Yao, D., & He, Y. (2025). Pollution characteristics and ecological risk assessment of typical heavy metals in the soil of the heavy industrial city Baotou. Processes, 13(1), 170. [Crossref]

Clesceri, L. S. (Ed.). (2011). Standard methods for the examination of water and wastewater (22nd ed.). American Public Health Association.

Clinical and Laboratory Standards Institute. (2022). Performance standards for antimicrobial susceptibility testing (32nd ed.; CLSI supplement M100).

Czekalski, N., Berthold, T., Caucci, S., Egli, A., & Burgmann, H. (2012). Increased levels of multiresistant bacteria and resistance genes after wastewater treatment and their dissemination into Lake Geneva, Switzerland. Frontiers in Microbiology, 3, 106. [Crossref]

Datta, K., Chakraborty, S., & Roychoudhury, A. (2025). Management of soil, waste and water in the context of global climate change. In Environmental nexus for resource management (pp. 1–26). CRC Press. [Crossref]

Department of Water Affairs and Forestry (DWAF). (2002). Quality of domestic water supplies. Treatment guide (Vol. 4; TT 1181/02). Water Research Commission.

Dhawale O. G. and LaMaster, B. H. (2003) Sanitation in Relation to Prevalence of Waterborne Diseases in Mbeere, Embu County, Kenya. IOSR Journal of Environmental Science, Toxicology and Food Technology, 10, 59-65

Dore, M., Singh, R., Khaleghi-Moghadam, A., & Achari, A. (2013). Cost differentials and scale for newer water treatment technologies. International Journal of Water Resources and Environmental Engineering, 5(2), 100–109.

Drewes, J. E., Reinhard, M., & Fox, P. (2003). Comparing microfiltration-reverse osmosis and soil-aquifer treatment for indirect potable reuse of water. Water Research, 37(15), 3612–3621. [Crossref]

Durham, H. E. (2001). A simple method for demonstrating the production of gas by bacteria. British Medical Journal, 1(1952), 1387. [Crossref]

Eckner, K. F. (2002). Comparison of membrane filtration and multiple-tube fermentation by the Colilert and Enterolert methods for detection of waterborne coliform bacteria, Escherichia coli and enterococci used in drinking and bathing water quality monitoring in southern Sweden. Applied and Environmental Microbiology, 64(8), 3079–3083. [Crossref]

Efuntoye, O., & Apanpa, O. (2010). Status of contamination and antibiotic resistance of bacteria from well water in Ago-Iwoye, Nigeria. Journal of Applied Biosciences, 35, 2244–2250.

Environment Agency. (2012). The microbiology of drinking water part 7 - Methods for the enumeration of heterotrophic bacteria.

European Committee on Antimicrobial Susceptibility Testing. (2013). Antimicrobial susceptibility testing EUCAST disk diffusion method (Version 3.0).

Feary, T. W., Sturtevant, A. B., Jr., & Lankford, J. (2009). Antibiotic resistant coliforms in fresh and salt water. Archives of Environmental & Occupational Health, 34(1), 25–30. [Crossref]

Feng, P., Weagant, S. D., & Grant, M. A. (2013). Enumeration of Escherichia coli and the coliform bacteria. In Bacteriological analytical manual (8th ed.). FDA/Center for Food Safety & Applied Nutrition.

Francy, D. S., Darner, R. A., & Myers, D. N. (2013). Escherichia coli and fecal coliform bacteria as indicators of recreational water quality (Water-Resources Investigations Report 93-4083).

Frost, I., Smith, W. P. J., Mitri, S., Millan, A. S., Davit, Y., Osborne, J. M., & Foster, K. R. (2018). Cooperation, competition and antibiotic resistance in bacterial colonies. The ISME Journal, 12(6), 1582–1593. [Crossref]

Geldreich, E. E. (1997). Bacterial populations and indicator concepts in feces, sewage, stormwater and solid wastes. In G. Berg (Ed.), Indicators of viruses in water and food (pp. 51–97). Ann Arbor Science.

Geldreich, E. E. (1999). Sanitary significance of fecal coliforms in the environment (Water pollution control research series). U.S. Dept. of the Interior, Federal Water Pollution Control Administration.

George, M., & Garrity, G. M. (Eds.). (2001). The gammaproteobacteria. In Bergey’s manual of systematic bacteriology (2nd ed., Vol. 2, pp. 1108). Williams & Wilkins.

Goula, A. M., Kostoglou, M., Karapantsios, T. D., & Zouboulis, A. I. (2008). A CFD methodology for the design of sedimentation tanks in potable water treatment: Case study: The influence of a feed flow control baffle. Chemical Engineering Journal, 140(1–3), 110–121. [Crossref]

Gregory, R., & Edzwald, J. K. (2010). Sedimentation and flotation. In Water quality and treatment: A handbook on drinking water (6th ed.). McGraw-Hill.

Guo, C., Wang, K., Hou, S., Wan, L., Lv, J., Zhang, Y., Qu, X., Chen, S., & Xu, J. (2017). H2O2 and/or TiO2 photocatalysis under UV irradiation for the removal of antibiotic resistant bacteria and their antibiotic resistance genes. Journal of Hazardous Materials, 323(Pt A), 710–718. [Crossref]

Hoffmann, H., Sturenburg, E., Heesemann, J., & Roggenkamp, A. (2006). Prevalence of extended-spectrum β-lactamases in isolates of the Enterobacter cloacae complex from German hospitals. Clinical Microbiology and Infection, 12(4), 322–330. [Crossref]

Horrocks, W. H. (2002). An introduction to the bacteriological examination of water. J. & A. Churchill.

Hudault, S., Guignot, J., & Servin, A. L. (2001). Escherichia coli strains colonizing the gastrointestinal tract protect germ-free mice against Salmonella typhimurium. Gut, 49(1), 47–55. [Crossref]

Hudzicki, J. (2009). Kirby-Bauer disk diffusion susceptibility test protocol. American Society for Microbiology.

Hunter Water. (2006). Water treatment processes. [Link]

Hutchinson, M., & Ridgway, J. W. (1998). Microbiological aspects of drinking water supplies. In Academic Press (p. 180).

Idehen, O. (2020). A comparative investigation of groundwater contamination in typical dumpsites and cemetery using ERT and physicochemical analysis of water in Benin metropolis, Nigeria. Journal of Geoscience and Environment Protection, 8, 72–85. [Crossref]

International Water Association. (2010). Sedimentation & flotation. American Water Works Association.

Iwane, T., Urase, T., & Yamamoto, K. (2001). Possible impact of treated wastewater discharge on incidence of antibiotic resistant bacteria in river water. Water Science and Technology, 43(2), 91–99. [Crossref]

Janse van Rensburg, S., Barnard, S., & Kruger, M. (2016). Challenges in the potable water industry due to changes in source water quality: Case study of Midvaal Water Company, South Africa. Water SA, 42(2), 633–640. [Crossref]

Jansen, J. L. C., Tanghe, T., & Verstraete, W. (1997). Micropollutants: A bottleneck in sustainable wastewater treatment. Water Science and Technology, 35(10), 13–26. [Crossref]

Jungfer, C., Schwartz, T., & Obst, U. (2007). UV-induced dark repair mechanisms in bacteria associated with drinking water. Water Research, 41(1), 188–196. [Crossref]

Krieg, N. R., & Holt, J. G. (Eds.). (1998). Bergey’s manual of systematic bacteriology (Vol. 1). Williams & Wilkins.

Kutlu, B., Sesli, A., Tepe, R., & Mutlu, E. (2015). Assessment of physicochemical water quality of Birecik Dam, Şanlıurfa, South-Eastern Anatolia Region, Turkey. Turkish Journal of Agriculture - Food Science and Technology, 3(7), 623–628. [Crossref]

Lazarus, A. M. (2008). Analysis of water consumption pattern among residential areas in Gombe Metropolis. Continental Journal of Applied Sciences, 3, 77–84.

Lechevallier, M. and Kwok-Keung, A. (2018) Water treatment and pathogen control: Process efficiency in achieving safe drinking water. World Health Organization, IWA Publishers, London, UK.

LeChevallier, M. W., & Au, K.-K. (2004). Water treatment and pathogen control: Process efficiency in achieving safe drinking water. World Health Organization.

LeChevallier, M. W., Karim, M. R., & Abbaszadegan, M. (2003). Potentials for pathogens intrusion during pressure transients. Journal - American Water Works Association, 95(5), 134–146. [Crossref]

Lechevallier, M., Karim, M. R., and Abbaszadegan, M. (2023) Potentials for Pathogens Intrusion During Pressure Transients. American Journal of Water Works Association, 95 (5), 134-146. [Crossref]

Li, B., & Webster, T. J. (2018). Bacteria antibiotic resistance: New challenges and opportunities for implant-associated orthopedic infections. Journal of Orthopaedic Research, 36(1), 22–32. [Crossref]

MacConkey, A. T. (1905). Lactose-fermenting bacteria in faeces. The Journal of Hygiene, 5(3), 333–379. [Crossref]

Magara, Y. (2000). Basic concepts and definitions in water quality and standards. Water Quality and Standards, 1, 29–35.

Manga, S. B., & Oyeleke, S. B. (2008). Essential of laboratory practical in microbiology. Usmanu Danfodiyo University.

Manhas, N. S. (2025). India and China’s approach to transboundary river pollutants and their impact on human health. In Intersecting realities of health resilience and governance in India: Emerging domestic and global perspectives (pp. 177–197). Springer Nature Singapore. [Crossref]

Mathew, B. B., & Krishnamurthy, N. B. (2017). Water constituents and treatment methods. Research & Reviews: A Journal of Structural Engineering, 4(2), 53–60.

Maurel, A. (2006). Seawater/Brackish water desalination and other non-conventional processes for water supply (2nd ed.). Lavoisier.

McFeters, G. A. (1990). Enumeration, occurrence, and significance of injured indicator bacteria in drinking water. In Drinking water microbiology (pp. 478–492). Springer. [Crossref]

Miller, R. A., Jian, J., Beno, S. M., Wiedmann, M., & Kovac, J. (2018). Intra-clade variability in toxin production and cytotoxicity of Bacillus cereus group type strains and dairy-associated isolates. Applied and Environmental Microbiology, 84(6), e02479-17. [Crossref]

Momba, M. N. B., Obi, C. L., & Thompson, P. (2009). Survey of disinfection efficiency of small drinking water treatment plants: Challenges facing small water treatment plants in South Africa. Water SA, 35(4), 485–493. [Crossref]

Morrison, S. (2009). Midvaal, a case study: The influence of ozone on water purification processes [Master’s thesis, North-West University].

National Population Commission (2022) House to House Survey Census. A tools for National Development Report. 110-120

Oh, J., Salcedo, D. E., Medriano, C. A., & Kim, S. (2014). The effect of tetracycline in the antibiotic resistant gene transfer before and after ozone disinfection. Desalination and Water Treatment, 57(2), 1–5. [Crossref]

Ohwo, O. (2014). Impact of pipe distribution network on the quality of tap water in Ojota, Lagos State, Nigeria. American Journal of Water Resources, 2(5), 110–117. [Crossref]

Okoh, A. I., Odjadjare, E. E., Igbinosa, E. O., & Osode, A. N. (2007). Wastewater treatment plants as a source of microbial pathogens in receiving watersheds. African Journal of Biotechnology, 6(25), 2932–2944. [Crossref]

Ramasamy, R., Subha, A. T. S., Abinaya, R. R., Muthusamy, K. K., Johney, J., & Ragunathan, R. (2018). Study on the prevalence of antibiotic resistant bacteria from drinking water. International Journal of Applied Science and Biotechnology, 6(3), 279–284. [Crossref]

Reid, G., & Gan, B. S. (2001). Can bacterial interference prevent infection? Trends in Microbiology, 9(9), 424–428. [Crossref]

Rodrigues, L., & Pacheco, A. (2010). Groundwater contamination from cemeteries-Cases of study. In Environmental 2010. Situation and perspective for the European Union. Paper C 03. [Link]

Saminu, A., Soho, U., Haruna, G., & Sagir, L. (2013). Design and construction of a model sedimentation tank using existing slow sand filter for NDA treatment plant. International Journal of Engineering Sciences and Research Technology, 2(7), 1694–1699.

Schutte, F. (2006). Handbook for the operation of water treatment works (TT 265/06). Water Research Commission.

Sesugh, A., Idowu, O. E., Titus, A., Zack, M. O., & Joseph, T. (2019). Physicochemical and heavy metal analysis of well water obtained from selected settlements around Dangote cement factory in Gboko, Nigeria. ChemistrySearch Journal, 10(2), 94–100.

Shah, C. R. (2017). Physical, chemical and biological parameters of water determine its quality. International Journal of Current Trends in Science and Technology, 7(6), 35–40.

Shi, P., Jia, S., Zhang, X.-X., Zhang, T., Cheng, S., & Li, A. (2013). Metagenomic insights into chlorination effects on microbial antibiotic resistance in drinking water. Water Research, 47(1), 111–120. [Crossref]

Singh, A. K., Das, S., Singh, S., Pradhan, N., Gajamer, V. A., & Kumar, S. (2019). Physicochemical parameters and alarming coliform count of the potable water of Eastern Himalayan State Sikkim: An indication of severe fecal contamination and immediate health risk. Frontiers in Public Health, 7, 174. [Crossref]

Sokoto State Water Board. (2015). Updated manual (pp. 1–40).

Stanfield, G., LeChevallier, M., & Snozzi, M. (2003). Treatment efficiency. In Assessing microbial safety of drinking water: Improving approaches and methods. IWA Publishing.

Sultana, S., Sultana, N., Moniruzzaman, M., Dastagir, M. R., & Hossain, M. K. (2025). Unmasking heavy metal contamination: Tracing, risk estimating and source fingerprinting from coastal sediments of the Payra River in Bangladesh. Marine Pollution Bulletin, 211, 117455. [Crossref]

Swanepoel, A., du Preez, H. H., & Cloete, N. (2017). The occurrence and removal of algae (including cyanobacteria) and their related organic compounds from source water in Vaalkop Dam with conventional and advanced drinking water treatment processes. Water SA, 43(1), 67–80. [Crossref]

Tazri, Z., Sakib, S., Das, R., Faruque, M. H., Hossain, A., Hosen, M. M., & Habibullah-Al-Mamun, M. (2025). Heavy metal contamination in a transboundary river: ecological and human health risk assessment. International Journal of Environmental Analytical Chemistry. [Crossref]

Tong, J., & Wei, Y. (2012). State-of-the-art removal of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARG) in wastewater treatment plants (WWTPs). Huan Jing Ke Xue, 33(11), 2650–2659.

United States Environmental Protection Agency. (2011). Basic information about disinfectants in drinking water.

United States Environmental Protection Agency. (2012). Report of task force on guide standard and protocol for testing microbiological water purifiers (pp. 1–29).

Walker, B. O., Angelo, M. and Sungpyo, Kim. (2012) The effect of tetracycline in the antibiotic resistant gene transfer before and after ozone disinfection. International Journal of Microbiology, 57(2):1-5

Yasin, M. Y., Ketema, T., & Bacha, K. (2015). Physico-chemical and bacteriological quality of drinking water of different sources, Jimma zone, Southwest Ethiopia. BMC Research Notes, 8, 541. [Crossref]