Research article · 2024 · Full text
International Journal of Geography Geology and EnvironmentAnalysis of water quality from boreholes within Africa University, Mutasa district, Zimbabwe
Volume 6(1) · Pages 384–390 · DOI: 10.22271/27067483.2024.v6.i1e.244 ↗
Research areasWater Quality and Pollution Assessment
Abstract
Author-writtenGroundwater, which is mainly extracted through boreholes, is considered the most reliable source of drinking water in many developing countries. This study evaluated borehole drinking water quality. The assessment was based on the laboratory analysis of sampled boreholes and comparing the findings to the recommended values for drinking water quality established by the World Health Organization (WHO). The laboratory analysis was based on the physicochemical and bacteriological water quality of five boreholes water. The water quality parameters measured were: the potential of hydrogen (pH), turbidity, electrical conductivity (EC), magnesium (Mg), zinc (Zn), iron (Fe), mercury (Hg), and total coliforms. The results showed that the analyzed total coliform, for B1, B2, B3, B4, and B5 were above the WHO’s recommendation for potable water of 0.00 count per 100 ml, which is an indication of fecal contamination in the water sampled. However, physicochemical and heavy metals quality analysis of all selected parameters were within the WHO's recommendation for potable water, except for iron in borehole two (B2), and mercury for all water samples. The study recommends a sanitary survey around boreholes to determine the sources of contamination. The results underscore the importance of implementing comprehensive water quality monitoring programs to identify and address the different types of contaminants in drinking water.
Summary
Source-checkedPlain-language reading of the full paper, prepared with AI and checked against the text. Each point links to the authors' own words.
Why it matters
- In many developing countries, groundwater extracted via boreholes is viewed as the most dependable source of drinking water. View evidence ↗
- Contaminants in borehole water used for consumption can pose significant threats to community health and well-being. View evidence ↗
- Groundwater is highly vulnerable to pollution, which degrades its quality and necessitates analysis of physical, chemical, and biological parameters to determine suitability. View evidence ↗
The question
- The study aimed to evaluate the quality of borehole drinking water by comparing laboratory analysis results against World Health Organization (WHO) recommended values. View evidence ↗
What they did
- Water samples were collected from five distinct boreholes, labeled B1 through B5. View evidence ↗
- The research employed a Complete Randomized Design, with measurements taken on a weekly basis for three weeks. View evidence ↗
- The measured parameters included pH, turbidity, electrical conductivity (EC), magnesium, zinc, iron, mercury, and total coliforms. View evidence ↗
- Analysis was performed using a pH meter, conductivity meter, and turbidimetric meter for basic physical properties, an atomic absorption spectrophotometer for metals, and the membrane Filtration Method for coliforms. View evidence ↗
What they found
- The pH values of the samples ranged from 6.68 to 7.41, which falls within the WHO guideline range of 6.5 to 8.5. View evidence ↗
- Electrical conductivity (EC) values ranged from 396 to 667 μS/cm, remaining below the WHO limit of 1000 μS/cm. View evidence ↗
- Magnesium concentrations ranged from 1.039 mg/l to 6.153 mg/L, which is well below the WHO maximum permissible value of 50 mg/l. View evidence ↗
- While most samples were within the WHO guideline of 0.3 mg/l, borehole B2 exceeded this limit with an iron concentration of 0.404 mg/l. View evidence ↗
- Zinc levels ranged from 0.002 to 0.019 mg/l, which is within the WHO permissible limit of 5 mg/l. View evidence ↗
- All five boreholes exceeded the WHO recommended zero value for total coliforms, with all samples showing levels greater than 16 per 100 ml. View evidence ↗
What it means
- Because total coliforms, mercury, and some iron levels exceeded WHO standards, the authors conclude there is a need for comprehensive monitoring, improved sanitation, and water treatment. View evidence ↗
- The authors recommend conducting sanitary surveys around the boreholes to identify the specific sources of contamination. View evidence ↗
Visual summary
2 visualsIllustrations explain the paper; charts are replotted from the paper's own table values.
EC: Borehole 1 vs Borehole 2 vs Borehole 3 vs Borehole 4 vs Borehole 5
Replotted from Table 1 (page 3) of the original paper. Every bar is the paper's own table value.
View source evidence ↗
Total coliforms: Borehole 1 vs Borehole 2 vs Borehole 3 vs Borehole 4 vs Borehole 5
Replotted from Table 3 (page 3) of the original paper. Every bar is the paper's own table value.
View source evidence ↗Figures & tables
From the original paper
Table 1
Table 2
Table 3
Table 4
Table 5
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8Introduction
Although water is regarded as an important resource for all living organisms and their environment, it is not of the recommended quality and is not accessible to a large number of people (Nkansah, Boadi, & Mercy, 2010) [5] . Boreholes water designated for consumption purposes may be potentially contaminated with different pollutants. Existence of these contaminants in water sources poses significant threats to the well-being and health of the community. Assessing water quality ensures the safety and sustainability of water resources. Gaging the physicochemical and biological parameters of water quality enables evaluation of the various physicochemical parameters, including pH, temperature, electrical conductivity, turbidity, dissolved oxygen, total dissolved solids, and heavy metals such as mercury. These parameters provide important information about the overall characteristics of the water and help in understanding its suitability for various purposes. The study aimed to analyze water samples for the presence of contaminants, including heavy metals, organic pollutants, and pathogens. Identify the types and concentrations of contaminants, provides information on the potential risks associated with water usage. Comparison with the present regulatory standards provides a basis for evaluating the compliance of the water sources with the established benchmarks for quality and recognizing areas where remedial actions are critical. Assessing water quality ensures the safety and sustainability of water resources. Gaging the physicochemical and biological parameters of water quality necessitates the evaluation of various physicochemical parameters, comprising of pH, temperature, electrical conductivity, turbidity, dissolved oxygen, total dissolved solids, and heavy metals such as mercury. These parameters provide important information about the overall characteristics of the water and help in understanding its suitability for various purposes. The study aimed at analyzing water samples for the presence of contaminants, including heavy metals, organic pollutants, and pathogens, and identify the types and concentrations of contaminants, which assists in assessing the potential risks associated with water usage. Comparison with the present regulatory standards provides a basis for evaluating the compliance of the water sources with the established benchmarks for quality and recognizing areas where remedial actions might be indispensable. The analysis of water quality from boreholes holds a significant implication for public health and environmental sustainability. Understanding the suitability of the water for consumption and identifying potential contaminants, allows informed decision-making regarding water treatment and usage. Due to the high groundwater vulnerability to pollution, which degrades its quality, this study aimed at analyzing the physical, chemical, and biological parameters to establish the suitability of the boreholes water.
Methodology Study site:
The site of the boreholes studied falls within the coordinates of approximately 18°53' to 19° 10' south latitude and 32° 24' to 32° 48' longitudes.
Research Design
A Complete Randomized Design was used in the study and measurements were taken weekly for three weeks.
Parameters Measured
Total coliforms, potential hydrogen, electrical conductivity, Turbidity, magnesium, and heavy metals including, zinc, mercury, and iron, were determined.
Determination protocol
Water samples were collected from 5 different boreholes and labeled accordingly. The 5 boreholes were designated as B1 to B5. Samples for physicochemical and heavy metals analysis were collected in clean 500 ml plastic bottles while autoclaved bottles were used for bacteriological samples. Data on pH, turbidity, electrical conductivity, magnesium, iron, zinc, mercury as well as total coliforms were collected and measured. pH meter, conductivity meter, and turbidimetric meter were used to determine pH, conductivity and turbidity respectively. Magnesium, iron, zinc, and mercury were determined using an atomic absorption spectrophotometer. The membrane Filtration Method was used to determine total coliforms. The buffer solutions used for calibration were pH 4.0, pH 7.0, and pH 10.0. The pH electrode was rinsed with distilled water immersed into the water sample and fully submerged without touching the sides or the bottom of the container to prevent the accuracy of the measurements. After standardization the readings were recorded as displayed on the screen.
Turbidity determination
Water samples were transferred into the sample cell turbidity meter up to the horizontal mark, then wiped with tissue paper and subsequently placed in the turbidity meter such that the vertical mark in the sample cell coincided with the mark in the turbidity meter, and covered. The readings displayed on the screen were recorded.
Electrical conductivity determination
The conductivity meter was calibrated before use and the conductivity probe was rinsed with distilled water and submerged in water samples ensuring that it did not reach the bottom or the sides of the container. After stabilization, the EC meter displayed consistent conductivity values that were recorded.
Alkali, Alkaline, and Heavy metals determination of 5.0 ml of nitric acid was added to 100 mL of water sample in 250 mL conical flask. The mixture was evaporated to half of its volume on a hot plate after which it was allowed to cool before filtering. The digestion water samples were analyzed for the presence of magnesium, iron, zinc, or mercury using atomic absorption spectrophotometer. The concentration of each heavy metals was calculated using the standard calibration plot for each metal (Momodu & Chimezie, 2009) [4] .
Total coliforms Determination
The membrane filter, vacuum filtration manifold, petri dishes, and forceps were properly sterilized using ethanol and the methylated spirit flame before use. A bacterial growth medium, sterile pipettes, and an incubator set at 37 °C temperature were used. Pad dispenser's applicator was used to place the pad on the petri dishes. The media was applied to the pad and the petri dishes were closed to prevent multiplication of inappropriate bacteria. A membrane filter was placed on the filtration manifold to filter the water sample. 100 ml was transferred into the membrane filter. An extraction pump was used to draw the water sample through the filter. Bacteria were retained on the filter surface. The membrane filter was then transferred to the petri dishes containing the bacterial growth medium using sterile forceps. The Petri dishes were then incubated and set to a temperature of 37 °C for 24 hours to allow bacterial colonies to grow. After the incubation period, the petri dishes were carefully examined to count visible colonies that had grown on the membrane filter and differentiated coliform colonies (yellow) from other colonies.
Data Analysis
Data collected was analyzed using the following model:
Where µ is equal to overall mean effect t i is equal to true effect of the i th treatment e ij is equal to error term of the j th unit receiving i th treatment
Results
Tables 1, 2, and 3 shows the mean variations in water quality for Physical, Chemical, and bacteriological analysis within the three weeks of sampling. pH values ranged from 6.68 to 7.41, indicating slightly acidic to neutral conditions while Electrical conductivity (EC) values ranged from 396 to 667, indicating varying levels of dissolved salts. Turbidity values ranged from 0.49 to 1.63 NTU. Mean variations in water quality for heavy metals, magnesium, iron, zinc, and mercury concentrations varied across the different boreholes. Mean variations in water quality for bacteriological analysis. A bacterial indicator of water quality varied across the boreholes. Tables 4 and5 indicates that most parameters fall within the acceptable range, except for iron in borehole 2. Total coliforms and mercury in all samples exceeded the standards. The potential of hydrogen, turbidity, electrical conductivity, magnesium, iron, zinc, mercury, and total coliforms. are depicted in Figures 1 to 8
Discussion
Through the physical, chemical, and bacteriological quality analysis carried out it was evident that standards of the most water samples were within the World Health Organization's recommendation. However, Borehole B2 revealed a slightly high iron concentration. All water samples contained mercury traces and tested positive for pathogens, pointing to the importance of regular quality assessment measures by responsible agencies.
Potential of hydrogen
The pH of the water samples ranged from 6.68 to 7.41. The highest pH value of 7.41 was recorded in B5 and the lowest pH of 6.68 in B1. The pH values were generally within the WHO guideline value which ranges from 6.5 to 8.5. Low pH in groundwater is generally because of the presence of carbon dioxide which is produced in the soil by both aerobic and anaerobic microbial processes. CO 2 dissolve in water forming carbonic acid, which lowers the pH (Hussain, Gupta, & Pandey, 2017) [3] . Anthropogenic factors such as agricultural runoff can contribute to the introduction of acidic pollutants into groundwater affecting its pH. This might be the probable reason why the three boreholes had slightly acidic water. 40% of the boreholes' pH was identified to be slightly alkaline with pH values of 7.08 and 7.41 for B2 and B5. Anthropogenic factors and high mineral content such as sodium bicarbonate (NaHCO 3 ) can raise groundwater pH, which is considered to be the most significant parameter determining the corrosive nature of the water. Exposure to extreme pH levels of less than 4 or higher than 11 can irritate mucous membranes and the eyes. The pH of the boreholes was generally within the WHO guideline value which ranges from 6.5 to 8.5) indicating permissibility for use.
Electrical conductivity
Conductivity is generally affected by the presence of dissolved ions in water. The significance of EC is its measure of salinity, which basically affects the taste and hence, impacts the user acceptance of the water (Ahmed, et al., 2010). The EC values for the samples varied from 396 to 667 μS/cm which compares favorably to the limit of electrical conductivity value (1000 μS/cm) in drinking water as per WHO guidelines indicating the favorability for drinking and agricultural purposes.
Turbidity
The maximum limit of turbidity in drinking water per WHO guidelines is 5.0 NTU. All borehole water samples had turbidity within the recommended value ranging between 0.49 and 1.63. Therefore, all the studied boreholes' water turbidity level was considered to be satisfactory for consumption.
Magnesium
As the maximum concentration of magnesium recommended by WHO is 50 mg/ for drinking water, the concentration of magnesium ions (1.039 mg/l to 6.153 mg/L) is below the maximum recommended permissible value.
Iron
Iron concentration was generally found within the WHO guideline value of 0.3 mg/l. However, the concentration of iron in borehole B2 (0.404 mg/l) was well outside the WHO guideline value. As the mean iron concentration of the samples from the five boreholes was 0.118 mg/l, the water is considered satisfactory for consumption except the one from Borehole 2. Iron in groundwater may come from natural sources and steel pumps and casings (Samuel, Sixtus, & Sebiawu, 2014) [6] . A high amount of rainfall increases the concentration of iron in boreholes. The process of rainfall infiltrating into the soil and underlying geologic formations is known to dissolve iron leading into aquifers (Abubakar & Adekola, 2012) [2] . Consuming large amounts of iron causes iron overload which results in hemochromatosis known to damage organs of the body.
Zinc
Excess zinc can affect the taste, odor, and appearance of the water, making it less desirable to consumers. It also presents many health risks including, kidney and liver failure, blood urine, and anemia. As the permissible level of zinc in drinking water recommended by WHO is 5 mg/l, the values of Zinc obtained from the study (0.002 to 0.019 mg/l), which is within the permissible limits for drinking water.
Mercury
The maximum mercury value determined by WHO for drinking water is 0.006. The observed values for mercury ranging from 0.881 to 1.351 mg/l is higher than the permissible level implying that that water from the five boreholes is considered unsuitable for human consumption.
Total Coliforms
The total concentrations of coliform samples of water from five boreholes were more than the zero value recommended by WHO. The presence of coliforms in most of the samples may be associated with the absence of residual chlorine, which may be an indication that water had not been chlorinated. Low levels of coliforms (≤ 16 per 100 ml) may not be a threat to the health of consumers. However, levels of coliforms greater than 16 per 100 ml as observed in all water samples render the water insalubrious and undesirable as high levels of coliforms in water can cause the spread of waterborne diseases such as Dysentery, Gastroenteritis, ear infection, Typhoid, and Hepatitis.
Conclusion and Recommendation
As the total coliform count, iron levels and mercury concentration in all analyzed water sources exceeded the recommended values by World Health Organization's there is need for comprehensive water quality monitoring, improved sanitation practices, and appropriate treatment measures to ensure the provision of safe drinking water to safeguarding public health and preventing waterborne diseases.
Figures and tables from the paper
| Sample | Ph | EC | Turbidity |
|---|---|---|---|
| Borehole 1 | 6.68 | 396 | 0.49 |
| Borehole 2 | 7.08 | 667 | 1.63 |
| Borehole 3 | 6.77 | 518.6 | 0.74 |
| Borehole 4 | 6.8 | 613 | 0.92 |
| Borehole 5 | 7.41 | 636.6 | 1.36 |
Table text extracted from the original PDF; superscript letters are shown inline. The original table image is below.
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| Sample | Magnesium | Iron | Zinc | Mercury |
|---|---|---|---|---|
| Borehole 1 | 6.153 | 0.023 | 0.002 | 0.985 |
| Borehole 2 | 1.3 | 0.404 | 0.019 | 1.078 |
| Borehole 3 | 1.039 | 0.107 | 0.003 | 0.881 |
| Borehole 4 | 1.995 | 0.042 | 0.019 | 1.351 |
| Borehole 5 | 3.173 | 0.014 | 0.002 | 1.056 |
Table text extracted from the original PDF; superscript letters are shown inline. The original table image is below.
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| Sample | Total coliforms |
|---|---|
| Borehole 1 | 52 |
| Borehole 2 | 32 |
| Borehole 3 | 26 |
| Borehole 4 | 42 |
| Borehole 5 | 38 |
Table text extracted from the original PDF; superscript letters are shown inline. The original table image is below.
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| Physico-chemical parameters mg/l | B1 | B2 | B3 | B4 | B5 | WHO | Remarks |
|---|---|---|---|---|---|---|---|
| PH | 6.68 | 7.08 | 6.77 | 6.8 | 7.41 | 6.5-8.5 | Okay |
| EC | 396 | 667 | 518 | 613 | 636.6 | 1000 | Okay |
| Turbidity NTU | 0.49 | 1.6 | 0.74 | 0.92 | 1.36 | 5 | Okay |
| Magnesium | 6.153 | 1.3 | 1.039 | 1.99 | 3.173 | 50 | Okay |
| Iron | 0.023 | 0.404 | 0.107 | 0.042 | 0.014 | 0.3 | Okay Except B2 |
| Zinc | 0.002 | 0.019 | 0.003 | 0.019 | 0.002 | 5 | Okay |
| Mercury | 0.985 | 1.078 | 0.881 | 1.351 | 1.056 | 0.006 | Exceed |
| Total Coliforms | 51 | 31 | 26 | 42 | 37 | 0 | Exceed |
Table text extracted from the original PDF; superscript letters are shown inline. The original table image is below.
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| Parameter | Mean | Minimum | Maximum | Standard Deviation | WHO values |
|---|---|---|---|---|---|
| Ph | 6.94 | 6.68 | 7.41 | 0.26 | 6.5-8.5 |
| Turbidity | 1.02 | 0.49 | 1.63 | 0.41 | 5 |
| EC | 566.4 | 396 | 667 | 98.59 | 1000 |
| Magnesium | 2.73 | 6.15 | 1.03 | 1.86 | 50 |
| Iron | 0.11 | 0.01 | 0.4 | 0.14 | 0.3 |
| Zinc | 0.009 | 0.002 | 0.019 | 0.008 | 5 |
| Mercury | 1.07 | 0.881 | 1.35 | 1.15 | 0.006 |
| Total coliforms | 37.4 | 26 | 52 | 8.89 | 0 |
Table text extracted from the original PDF; superscript letters are shown inline. The original table image is below.
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References
6 in the original paper- Ahmed MJ, Haque MR, Siraj S, Bhuiyan MR, Bhattacharjee SC, Islam S. Physicochemical assessment of surface and groundwater quality of the Greater Chittagong Region of Bangladesh. Pakistan Journal of Analytical & Environmental Chemistry. 2010;11(2):0111.
- Abubakar B, Adekola O. Assessment of borehole water quality in Yola-Jimeta Metropolis, Nigeria. International Journal of Water Resources and Environmental Engineering. 2012;9(4):287-293.
- Hussain J, Gupta N, Pandey P. Effect of physicochemical and biological parameters on the quality of river water of Narmada, Madhya Pradesh, India. National Water Science Research Center. 2017;31(1):11-23. Available from:
- Momodu MA, Chimezie A. Heavy metal contamination of groundwater: The Surulere case study. Research Journal of Environmental and Earth Sciences. 2010 Jan 10;2(1):39-43.
- Nkansah AM, Boadi N, Mercy B. Assessment of the quality of water from hand-dug wells in Ghana. Environmental Health Insights. 2010;4(4):7-12.
- Samuel AF, Sixtus B, Sebiawu E. A physico-chemical and bacteriological analysis of borehole water samples from the Wa Municipality of the Upper West Region, Ghana. 2018;26(1):1-15.
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