The study assessed the physico-chemical quality of selected drinking water sources (springs, boreholes, shallow wells and rainfall) in Mbarara municipality with respect to World Health Organization (WHO) drinking water guidelines and other guidelines in light of the increased anthropogenic activities in the municipality. A total of 70 water samples were collected from purposively selected boreholes, springs, wells and rainwater in Nyamitanga, Kamukuzi and Kakoba divisions of Mbarara municipality with various human activities. The samples were analysed for physico-chemical parameters: Temperature, pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Total Dissolved Solids (TDS), Electrical Conductivity (EC) and Total hardness using American Public Health Association (APHA) standard methods. The mean temperature and pH ranged between 18.07 °C - 23.45 °C and 5.74 - 7.54, respectively. The mean DO values were found to be between 4.84 and 12.86 mg/l; whereas mean BOD was within the range of 1.83 - 7.71 mg/l. The mean TDS and EC of the water samples ranged, between 33.40 - 569.20 mg/l and 29.30 - 1139.90 μS/cm respectively. Furthermore, the lowest and highest mean total hardness were 70.00 and 264.00 mg/l, respectively. The recorded mean water temperatures for each of the water sources were above the WHO threshold temperature (15 °C) which makes drinking water palatable. Boreholes in Nyamitanga and Shuhaddea Secondary Schools, spring in Kiswahili, well in Kisenyi and rainwater in Mbarara University of Science and Technology (MUST) had mean pH below the WHO minimum guideline value (6.5) hence acidic. Borehole in Nyamitanga secondary school, spring in Kisenyi, shallow well in Nyamitanga and the rainwater in MUST had mean DO values below the WHO range (10 - 12 mg/l). Borehole in Shuhaddea Secondary School and the well in Kisenyi had average BOD values above the range of European Union guideline values (3 - 6 mg/l). TDS and EC of all the water sources were below the WHO maximum guideline limits of 1000 mg/l and 1500 μs/cm respectively. Total hardness was also below the WHO harmless limit of 1000 mg/l. However rainwater in MUST was moderately soft while the other drinking water sources exhibited moderate to full total hardness. The physicochemical parameters of some of the selected water sources in Mbarara municipality have been compromised mainly by the increased human activities especially croplands, latrines, landfills, transportation, animal and municipal wastes at the vicinity of the water sources. Mbarara municipal council should therefore ensure proper sanitation and water safety plans for these drinking water sources to avoid further contamination from the human activities.
Water is a natural resource which forms an essential component of life [
The study was conducted in Mbarara municipality located in Mbarara District, South Western Uganda, 290 km from Kampala (capital city of Uganda) on Kampala-Kabale road at longitude 30.6582˚ and latitude 0.6132˚ [
The fairly densely populated Mbarara municipality of about 194,973 people [
A 200 m radius was measured from the water sampling point using a tape measure and selected anthropogenic activities with great influence on water quality within a 200 m radius circumference along established line transects were ob-
served and noted. A 200 m radius from the sampling points of drinking water sources was chosen because it is the maximum distance for protection of a lake [
A total of 70 water samples were collected from the seven drinking water sources (2 boreholes, 2 springs, 2 wells (shallow well, deep well) and rainwater) with ten samples from each water source. The ten rainwater samples were collected directly from a rainfall after an hour of downpour in an open space to be used as a control. The water samples were collected in 300 ml sterile plastic bottles which were immediately analysed for most of the physico-chemical parameters.
The water samples were analysed for physico-chemical parameters; Temperature, pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Total Dissolved Solids (TDS), Electrical Conductivity (EC) and Total hardness using standard methods [
For BOD, four 300 ml glass stoppered BOD bottles were used to determine the Biological Oxygen Demand in the water samples. To two of the bottles, water sample (10 ml) was added and filled to the mark with dilution water while the other two were filled to the mark only with dilution water to act as blank solutions. All bottles were immediately stoppered and labelled. One bottle with blank solution and another with the water sample were placed in the incubator and kept for 5 days at 21˚C. The other two bottles (one with a blank solution and the other with the water sample solution) were immediately analysed for dissolved oxygen (DO) and their values noted down as B0 and D0 respectively. After 5 days the blank solution and water sample solution were removed from the incubator and analysed for dissolved oxygen (DO) with their DO values noted as B5 and D5 respectively.
The BOD was then calculated using the formular, BOD = ((DO − BO) − (D5 − B5))/P where B0 is dissolved oxygen for blank solution on first day; D0 is dissolved oxygen for sample solution on first day; D5 is dissolved oxygen for sample solution on fifth day; B5 is dissolved oxygen for blank solution on fifth day; P is decimal volumetric fraction sample used..
The results of the proximity (m) and coverage (m2) of the anthropogenic activities as well as the minimum, maximum, standard deviation, mean, standard error of the mean and coefficient of variation values of the measured physico-chemical parameters were tabulated. The physico-chemical parameters were compared with set standards, WHO and European Union guidelines for drinking water. Mean differences of the parameters between water sources were determined using one-way ANOVA (F) test and relationships between the physico-chemical parameters established using Pearson product-moment correlation coefficient (r) at 5% level of significance. The data presentations and analysis were done by using Microsoft Excel 2007 and SPSS 20.0 Statistical packages.
This section presents the findings of the study and discussion beginning with the anthropogenic activities in the vicinity of the drinking water sources followed by the physico-chemical quality of the water sources.
The identified anthropogenic activities within the vicinity of the drinking water sources with great impact on the quality of the water sources are presented in
Activities | Borehole (Nyam. S.S) | Borehole (Shud. S.S.) | Spring (Kisw) | Spring (Kise) | Well (Kise) | S. well (Nyam) | |
---|---|---|---|---|---|---|---|
Croplands | Proximity | 24 | 35 | 12 | - | - | 1 |
Coverage | 2589 | 3970 | 207 | - | - | 3096 | |
Animal farms | Proximity | - | 23 | - | - | 2 | - |
Coverage | - | 8 | - | - | 27 | - | |
Latrine | Proximity | 37 | 53 | 17 | 4 | 20 | 2 |
Coverage | 148 | 185 | 370 | 370 | 222 | 256 | |
Settlements | Proximity | 16 | 54 | 17 | 8 | 16 | 3 |
Coverage | - | - | - | - | - | - | |
Land fills | Proximity | 12 | 33 | 58 | 11 | 12 | 7 |
Coverage | 149 | 67 | 387 | 442 | 211 | 158 | |
Brick laying | Proximity | - | - | - | - | - | 10 |
Coverage | - | - | - | - | - | 9 | |
Washing sites | Proximity | - | - | - | - | 10 | - |
Coverage | - | - | - | - | 21 | - | |
Municipal waste | Proximity | - | - | 4 | - | 26 | - |
Total coverage | 2886 | 4230 | 964 | 812 | 481 | 3519 |
Nyam. S.S: Nyamitanga Secondary School; Shud. S.S: Shuhaddea Secondary School; Kisw: Kiswahili; Kise: Kisenyi; Nyam: Nyamitanga; S. well: Shallow well; -: represents no anthropogenic activity.
shallow well in Nyamitanga while the furthest was situated 35 m from the borehole in Shuhaddea Secondary School though it had the highest coverage (3970 m2) as shown in
The increased anthropogenic activities (croplands, animal farms, latrine, settlements, landfills, brick laying, washing sites and municipal waste) within the vicinity (200 m) of the different drinking water sources could be attributed to the increased population as a result of urbanisation. This is in line with [
The descriptive statistics of the physico-chemical parameters of the selected drinking water sources and the comparisons among the water sources are summarized in
There were significant temperature variations (p < 0.05) in the water sources with low variability within the samples (CV = 1.38% - 4.84%). The highest mean temperature was recorded in spring (Kisenyi) and lowest in rainwater (MUST). Temperature is among the physico-chemical parameters useful in evaluating the quality of drinking water as it influences the overall quality of water (physico- chemical and biological characteristics) including the rate of chemical reactions in the water body, decrease in the solubility of gases and improving the tastes and colours of water [
Parameter (n = 10) | Water source | Min. | Max. | SD | Mean ± SE | CV (%) | p-value for F test | Guideline value |
---|---|---|---|---|---|---|---|---|
Temperature (oC) | Borehole (Nyam. S.S) | 22.30 | 23.50 | 0.57 | 22.98 ± 0.29 | 2.50 | 0.00 | 15˚C* |
Borehole (Shud. S.S) | 21.60 | 22.90 | 0.41 | 22.34 ± 0.13 | 1.84 | |||
Spring (Kisw) | 21.30 | 23.00 | 0.52 | 22.38 ± 0.16 | 2.32 | |||
Spring (Kise) | 22.60 | 24.90 | 0.72 | 23.45 ± 0.23 | 3.07 | |||
Well ( Kise) | 18.50 | 21.70 | 1.01 | 20.79 ± 0.32 | 4.84 | |||
Shallow well (Nyam) | 21.70 | 22.60 | 0.31 | 22.17 ± 0.10 | 1.38 | |||
Rainwater | 17.20 | 18.80 | 0.54 | 18.07 ± 0.17 | 2.98 | |||
pH | Borehole (Nyam. S.S) | 6.19 | 6.77 | 0.22 | 6.37 ± 0.07 | 3.42 | 0.00 | 6.5 - 9.5* |
Borehole (Shud. S.S) | 5.50 | 6.53 | 0.29 | 5.74 ± 0.09 | 5.06 | |||
Spring (Kisw) | 6.17 | 6.29 | 0.03 | 6.21 ± 0.01 | 0.56 | |||
Spring (Kise) | 6.65 | 7.02 | 0.14 | 6.77 ± 0.04 | 2.08 | |||
Well ( Kise) | 4.49 | 6.70 | 0.64 | 6.31 ± 0.20 | 10.18 | |||
Shallow well (Nyam) | 7.23 | 7.70 | 0.13 | 7.54 ± 0.04 | 1.71 | |||
Rainwater | 5.80 | 6.70 | 0.32 | 6.21 ± 0.10 | 5.16 | |||
Dissolved Oxygen (mg/L) | Borehole (Nyam. S.S) | 5.30 | 8.60 | 1.08 | 7.42 ± 0.34 | 14.57 | 0.00 | 10 - 12 mg/l* |
Borehole (Shud. S.S) | 5.10 | 14.20 | 2.83 | 10.41 ± 0.90 | 27.22 | |||
Spring (Kisw) | 8.00 | 15.60 | 3.15 | 10.28 ± 10 | 30.61 | |||
Spring (Kise) | 1.90 | 6.30 | 1.20 | 4.84 ± 0.38 | 24.76 | |||
Well ( Kise) | 9.00 | 18.10 | 3.01 | 12.86 ± 0.95 | 23.37 | |||
Shallow well (Nyam) | 3.20 | 6.30 | 1.01 | 5.07 ± 0.32 | 19.86 | |||
Rainwater | 9.30 | 10.00 | 0.22 | 9.54 ± 0.07 | 2.33 | |||
BOD (mg/L) | Borehole (Nyam. S.S) | 4.00 | 7.00 | 1.10 | 5.59 ± 0.35 | 19.60 | 0.00 | 3 - 6 mg/l*** |
Borehole (Shud. S.S) | 3.10 | 12.00 | 3.33 | 7.71 ± 1.05 | 43.19 | |||
Spring (Kisw) | 4.00 | 9.10 | 1.69 | 5.98 ± 0.54 | 28.34 | |||
Spring (Kise) | 0.50 | 3.10 | 0.86 | 2.16 ± 0.27 | 39.72 | |||
Well ( Kise) | 3.20 | 8.90 | 2.09 | 6.72 ± 0.66 | 31.10 | |||
Shallow well (Nyam) | 1.80 | 5.40 | 1.10 | 4.14 ± 0.35 | 26.59 | |||
Rainwater | 1.30 | 2.50 | 0.36 | 1.83 ± 0.11 | 19.79 | |||
Total Dissolved Solids (mg/L) | Borehole (Nyam. S.S) | 256.00 | 380.00 | 32.74 | 297.70 ± 10.35 | 11.00 | 0.00 | 1000 mg/l* |
Borehole (Shud. S.S) | 272.00 | 348.00 | 22.51 | 298.40 ± 7.12 | 7.54 | |||
Spring (Kisw) | 345.00 | 357.00 | 3.63 | 350.10 ± 1.15 | 1.04 | |||
Spring (Kise) | 557.00 | 579.00 | 6.61 | 569.20 ± 2.09 | 1.16 | |||
Well ( Kise) | 347.00 | 370.00 | 6.03 | 357.90 ± 1.91 | 1.68 | |||
Shallow well (Nyam) | 250.00 | 268.00 | 5.53 | 257.80 ± 1.75 | 2.15 | |||
Rainwater | 12.00 | 55.00 | 13.28 | 33.40 ± 4.20 | 39.78 |
Electrical Conductivity (μs/cm) | Borehole (Nyam. S.S) | 565.00 | 615.00 | 14.81 | 585.60 ± 4.68 | 2.53 | 0.00 | 1500 μs/cm* |
---|---|---|---|---|---|---|---|---|
Borehole (Shud. S.S) | 580.00 | 630.00 | 15.49 | 601.40 ± 4.90 | 2.58 | |||
Spring (Kisw) | 685.00 | 715.00 | 9.92 | 698.90 ± 3.14 | 1.42 | |||
Spring (Kise) | 1113.00 | 1152.00 | 10.89 | 1139.90 ± 3.44 | 0.96 | |||
Well ( Kise) | 708.00 | 730.00 | 7.98 | 717.80 ± 2.52 | 1.11 | |||
Shallow well (Nyam) | 409.00 | 553.00 | 37.17 | 508.70 ± 11.75 | 7.31 | |||
Rainwater | 16.00 | 47.00 | 10.09 | 29.30 ± 3.19 | 34.43 | |||
Total Hardness (mg/L) | Borehole (Nyam. S.S) | 215.00 | 285.00 | 33.81 | 264.00 ± 10.69 | 12.81 | 0.00 | 1000 mg/l** |
Borehole (Shud. S.S) | 140.00 | 215.00 | 38.73 | 185.00 ± 12.25 | 20.94 | |||
Spring (Kisw) | 215.00 | 285.00 | 33.81 | 236.00 ± 10.69 | 14.33 | |||
Spring (Kise) | 140.00 | 215.00 | 39.53 | 177.50 ± 12.50 | 22.27 | |||
Well (Kise) | 140.00 | 215.00 | 31.62 | 200.00 ± 10.00 | 15.81 | |||
Shallow well (Nyam) | 140.00 | 140.00 | 0.00 | 140.00 ± 0.00 | 0.00 | |||
Rainwater | 70.00 | 70.00 | 0.00 | 70.00 ± 0.00 | 0.00 |
Min.: Minimum; Max.: Maximum; SD: Standard deviation; SE: Standard error of the mean; CV: coefficient of variation; *: [
City, Uganda [
Statistically significant mean pH variations were observed among the seven water sources (p < 0.05) although there were low differences within samples for six water sources (CV < 10%) apart from the well in Kisenyi (CV = 10.18%). The highest mean pH was recorded in shallow well (Nyam) and the least in Borehole (Shud. S.S). The pH of water is a useful parameter as most biological activities take place only within a narrow range. As a result, any pH variations beyond an acceptable limit could be fatal to a particular organism [
Acid rains in Mbarara municipality resulting from SO2 and NOx emissions from urban traffic of cars [
However, the slightly higher mean pH value (7.54) in the shallow well in Nyamitanga (a surface water source) than other drinking water sources can be attributed to organic material and sediment runoff from the closely located surrounding croplands (1 m from the water source) as opposed to croplands around other water sources. The deposition of sediments and organic materials into the water causes a change in the carbonate-bicarbonate equilibrium in surface water causing a relatively higher pH beyond neutral [
DO concentrations showed significant variations (p < 0.05) among the water sources with highly variable values within samples for most of the water sources (CV > 10%) except for rainwater at MUST (CV = 2.33%). The highest and lowest mean DO concentrations were recorded in the well and spring at Kisenyi respectively. Dissolved oxygen (DO) is a very important parameter of water quality and an index of physical and biological process going on in water which favors solubility of oxygen [
The low DO in the shallow well in Nyamitanga can be attributed to increased decomposition of organic material from the closely situated surrounding croplands (1 m from the water source) though on the contrary, BOD does not reflect it despite the significant overall positive correlation with DO (r = 0.683, p < 0.05, n = 70). The low DO values in spring (Kise.), Borehole (Nyam. S.S) and Shallow well (Nyam) can be associated with the slightly elevated temperature values in these water sources. This is further supported by the overall significant negative correlation of temperature with DO (r = −0.454, p < 0.05, n = 70). Low DO values in drinking water samples have been attributed to the high temperature of the water [
BOD showed significant variations (p < 0.05) among the water sources and were very variable within samples for all the water sources (CV > 10%). The borehole at Shuhaddea Secondary School had the highest mean BOD and the least was in rainwater at Mbarara University of Science and Technology. BOD is the measure of the amount of dissolved oxygen required for the decomposition of organic compounds [
Total dissolved solids showed significant variations (p < 0.05) among the water sources and were less variable within samples for most of the water sources (CV < 10%) except for rainwater at MUST and borehole in Nyamitanga (CV > 10%). The spring water in Kisenyi also recorded notably the highest total dissolved solids while rainwater (MUST) had the least. Total dissolved solids (TDS) including carbonate, bicarbonate, chloride, sulphate, phosphate, nitrate, calcium, magnesium, sodium, organic ions and other ions determine the general nature of water quality [
There was a statistically significant difference (p < 0.05) among mean electrical conductivities of the different water sources with spring (Kise) having the highest extreme value and the least value was in rainwater (MUST). The within sample variation of the conductivities for six water sources were small (CV < 10%) except for rainwater at MUST (CV = 34.43%). Electrical conductivity is the ability of any medium, water in this case, to carry an electric current. The presence of dissolved solids such as calcium, chloride, and magnesium in water samples carries the electric current through water [
The notably higher mean conductivity in spring (Kise) than the other water sources corresponds to the high Total Dissolved Solids (TDS) in the spring water. This is further augmented by the overall significant positive correlation between conductivity and TDS (r = 0.996, p < 0.05, n = 70). This confirms that it is mainly the same ions that constitute TDS i.e. carbonate, bicarbonate, chloride, sulphate, phosphate, nitrate, calcium, magnesium, sodium, organic ions and other ions which lead to the conductivity of the water sources. The high temperature (23.45˚C) in spring (Kise) could have increased the dissolution of the ions leading to high TDS and conductivity as supported by the overall significant positive correlation (p < 0.05) of temperature with TDS (r = 0.762) and conductivity (r = 0.764).
There were significant variations (p < 0.05) in total hardness of the 7 water sources with borehole (Nyam. S.S) registering the highest value while the least was for rainwater (MUST). Total hardness values were highly variable within samples for most of the water sources (CV > 10%) except for shallow well in Nyamitanga and rainwater at MUST (CV = 0.00%). Calcium and magnesium dissolved in water are the two most common minerals that make water “hard” [
A range of physico-chemical parameters in most of the selected drinking water sources (boreholes, springs, wells, rainwater) in Mbarara Municipality have been compromised by anthropogenic activities (croplands, latrines, landfills, transportation, animal and municipal wastes) situated within the vicinity of these water sources.
The temperature of the water sources were above the WHO threshold temperature for palatable water.
The pH of boreholes in Nyamitanga and Shuhaddea Secondary Schools, spring in Kiswahili, well in Kisenyi and rainwater in Mbarara University of Science and Technology were below the WHO minimum guideline value hence acidic.
The dissolved oxygen levels of borehole in Nyamitanga secondary school, spring in Kisenyi, shallow well in Nyamitanga and the rainwater in Mbarara University of Science and Technology were below the WHO range thus less suitable for other aerobic aquatic life.
BOD values of borehole in Shuhaddea secondary school and the well in Kisenyi were above the European Union guideline value signifying a lot of decomposition of organic matter in these water sources.
The selected water sources (boreholes, springs, and wells) were found to have moderately hard and hard water from the total hardness measure hence undesirable for domestic uses like washing and boiling etc.
Mbarara municipal council should therefore ensure proper sanitation and water safety plans for these drinking water sources to avoid further contamination from the human activities.
The Authors would wish to acknowledge the support offered to them by the entire Department of Biology of Mbarara University of Science and Technology during the research and preparation of this paper.
Lukubye, B. and Andama, M. (2017) Physico-Chemical Quality of Selected Drinking Water Sources in Mbarara Municipality, Uganda. Journal of Water Resource and Protection, 9, 707-722. https://doi.org/10.4236/jwarp.2017.97047