This study was conducted to assess the drinking water quality of north Mecha district, Amhara Region, Ethiopia. 26 drinking water samples were collected from the water points of the dweller community in the dry seasons of 2020 and subjected to the analysis of physicochemical parameters, bacteriological parameters, and the level of trace metals. The analysis of physicochemical parameters and the trace metals was carried out following the standard procedures of the laboratory, and the bacteriological water qualities were measured using the membrane filtration method. The F−, NO3−, SO42−, and Cu levels of the water samples were within the permissible limits of the WHO and compulsory Ethiopian standard (CES). Depending on turbidity, 61.54% of the tested water samples crossed the WHO limit of drinking water quality, and 100% of the samples surpassed the limits of EPA. Based on iron and ammonia levels, 38.46%, and 100% of the studied water samples violated the environmental protection agency (EPA) guidelines; 23.07%, and 3.84%, of the samples surpassed the WHO and CES drinking water quality standards. In view of pH, 23.07% of the tested water samples were not within the safe limit of the WHO and CES. 92.31% of the studied water samples were not potable as coliform bacterium (thermo tolerant indicator bacterium) growth was detected. The study revealed that the water sources of the study area are not safe for drinking unless appropriate treatment measurements are taken. Higher values of water quality parameters for the water samples from Koga irrigation site than the values for the water samples from the study sites found out of the irrigation site indicated the pollution load of Koga irrigation on the water quality of the area.
Water is very vital for the endurance of all living organisms. However, it may be a source of several transmission and chronic human disease if it is exposed to bacteriological, chemical, and physical contaminants. Water plays a significant role on the growth of pathogens that have emerged and health problems: an estimation of 80–85% of the communicable disease is transmitted through water [
As stated by Boyd [
Heavy metals are released into the ecosystem from geogenic (natural alteration of the mineralized zone) and anthropogenic (mining, agrochemicals, and industrial effluents) activities [
Water quality is commonly defined by its physical, chemical, biological, and aesthetic (appearance and smell) characteristics. Water quality is closely linked to the surrounding environment and land use. Usually, water could be never pure and may be affected by agriculture, urban, industrial, recreation, and so on. The modification of natural stream flows and the weather or climate change can also have major impact on water quality. Groundwater is a major source of drinking water, and it can be vulnerable to contamination due to agriculture, urban, and industrial development. Microbial or chemical contamination of water cannot be detected by sense organ like sight, smell, or taste. The only way to know if water is contaminated with bacteria or chemicals is to test it in the laboratory. Testing all possible microbial pathogens in water is still very expensive and time-consuming. Therefore, testing the most common indicators such as total coliform, faecal coliforms, and
Living organisms need clean and safe water for their well beings. If the quality of water is compromised, an additional cost is needed for clean drinking water supply [
Thus, water quality and the risk to waterborne diseases are critical public health concerns in many developing countries. Close to a billion people, most living in the developing world, do not have access to safe and adequate water [
According to the reported literatures [
Unfortunately, in developing countries like Ethiopia, the drinking quality of water is continuously being contaminated and hazardous for human use due to high growth of population, expansion in industries, and throwing away of wastewater and chemical effluents into canals and other water sources. In Ethiopia, studies conducted in Dire Dawa and Jimma revealed 83.34% and 87.5% of water sample were positive for bacterial indicators, respectively [
In many parts of the country, rural residents use borehole or spring water for their domestic and drinking consumption without strict water quality monitoring [
The current study was conducted in four selected kebeles of North Mecha district: Midre Genet, Felege Birhan (found out of Koga irrigation), Inguti, and Kudmi (found in Koga irrigation). In a community of north Mecha district, Inguti and Kudmi kebeles, only 68.25% of the population (from the total population of 18,984) obtained drinking water from the protected areas, while the remaining 31.75% of the population use unprotected and river water sources including the dam canals of Koga irrigation. There are 37 different types of water points in the two kebeles. These are deep well, developed spring, and shallow well. Agrochemicals and fertilizers used by farmers in Koga irrigation site go off to the water points which the dweller communities use as their drinking water sources. Hence, the constructed community water providers are suspected to be contaminated as a result of agrochemicals and anthropological interventions in the area. To handle such problems, it is necessary to carry out water quality assessment, planning, and management. However, no attention was paid to the most sensitive and vulnerable compartment of ecosystem, i.e., the water quality of the area. Therefore, the aim of this study was to assess the quality of water from the indicated sources by comparing with the national and international standards, through the analysis of the physicochemical, biological parameters, and trace metal levels of the water samples. For comparison, drinking water samples were collected from Midre Genet and Felege Birhan kebeles found out of the irrigation project. This helps to determine the potability of drinking water in this area. It can also indicate the impacts of Koga irrigation agriculture activities on the physicochemical and biological quality of drinking water in the area.
The study was conducted in Mecha district, Amhara National Regional State, Ethiopia (Figure
Location map of the study areas.
As a result of this elevation difference, variables such as climate, vegetation, and soils show a discrepancy. The study area exhibit two major traditional climatic zones: the Dega (2300–3200 MASL) and Woyna Dega (1500–2300) MASL with mean annual rainfall of 1500–2200 mm [
Mecha district is a foundation for Koga watershed which is located in Tana subbasin, Eastern part of the Blue Nile. The rivers draining Koga watershed begin from Mount Wezem and flow into Gilgel Abay, which finally drains into Lake Tana. The high runoff and associated sediment flow from the upper part of this watershed and have serious consequences on the downstream users and water bodies (e.g., Lake Tana and reservoirs developed for irrigation). The watershed exhibits an elevation range of 1890–3200 meter above the sea level [
In response to increasing demand for food and contrastingly declining agricultural production in the study area, the Ethiopian government constructed Koga dam in Koga watershed to irrigate 7,000 ha land. The Koga irrigation project is found between 1892 and 2043 masl altitude with UTM coordinates of N 1,255,000, N 1,270,000, E 290,000, and E 300,000. The project area covers a total size of about 10,000 ha [
Land use of the study area is dominated by traditional subsistence peasant farming on individual holdings [
This study was a cross-sectional study to find out the physicochemical and bacteriological quality of drinking water sources found in Midre Genet, Felege Birhan (non-irrigated areas), and Inguti and Kudmi kebeles of agriculture irrigated areas. Prior to their use, all sampling materials including sample holders were washed with detergent, rinsed with distilled water, soaked with 10% HNO3 for 24 hr, rerinsed with deionized water, and finally air dried [
From different water sources of the dwellers, 26 water samples (twelve from deep well, eight from a shallow well, and six from protected spring) were collected. To estimate the effects of Koga irrigation on the drinking water quality of the area, 14 of the water samples (SW1-SW5, DW1-DW6, and DS1-DS3) were collected from Inguti and Kudmi kebeles which are found within the Koga irrigation project. For comparison, the remaining water samples (SW6-SW8, DW7-DW12, and DS4-DS6) were collected from Midre Genet and Felege Birhan kebeles found out of the irrigation project. Water samples were collected from three different points of each site using prerinsed 250 ml polyethylene bottles. Some physicochemical parameters of water samples were measured at the site, and samples from the three points of each site mixed in a one-liter polyethylene container to which 2 ml nitric acid was added to reduce adsorption of metals on to the walls of the plastic bottles. Sample bottles were then labeled for date of sampling and sampling site [
The pH meter (JENWAY model 370), EC meter (HANNA model Hi9033 multirange conductivity meter), hotplate, volumetric flask (100, 150 ml), filter paper (Whatman no. 1), spectrophotometer (Model DR 7100, Japan), dropper (LDPE 0.5–1 ml), sample cells (1 inch square, 10 ml), turbidometer (nephelometric), sample bottle, hand lens vacuum pump, Palintest Nitratest Tube (PT526, 20 ml), and Palintest photometer (
Nitric acid (69–72%), hydrogen peroxide (30%), hydrochloric acid (37%), lanthanium nitrate, calcium chloride (anhydrous), Palintest phosphate, HR tablets, SR tablets, deionized water (in 2% HNO3), sulfuric acid (98%), ferric chloride (hexahydrated), buffer solutions (pH: 4.7 and 7.01), distilled water, NitraVer 5 nitrate reagent powder Pillow, SPADNS reagent, ammonia salicylate reagent powder, Ammonia cyanurate reagent powder Pillow, PhosVer 3 phosphate reagent powder Pillow, FerroVer iron reagent powder Pillow, CuVer 3 cupper reagent powder Pillow, SulfaVer 4 sulfate reagent powder Pillow, and Lauryl sulfate broth were among the analytical grade chemicals used in the research.
The measurement of physicochemical parameters such as temperature, electrical conductivity, TDS, turbidity, and pH were carried out directly at the sampling sites using a portable conductivity meter, turbidometer, and pH meter.
The pH measurements were done after calibration of the pH electrode with buffer solutions. For electrical conductivity measurement, the EC electrode was calibrated using a standard solution of KCl after which the sample was taken from the source using a 100 ml plastic container and direct measurements were done. In situ measurement of turbidity was done using a turbidometer (nephelometric). Before analysis, prepared standards were used to calibrate the turbidometer in the desired range of accuracy using manufacturer’s operating instruction. 10 ml water sample was taken in cuvettes, and readings were taken in nephelometric turbidity units (NTU).
The nitrate, fluoride, ammonia, sulfate, phosphate, iron, and copper levels (mg/l) were determined using a spectrophotometer adjusted at different wave lengths. Nitrate was analyzed by the DR 2010 spectrophotometer instrument. For nitrate, the spectrophotometer was adjusted at 355 nm after which a square sample cell was filled with 10 ml of water sample, and one NitraVer 5 nitrate reagent powder Pillow was added, swirled, and waited until the reaction took place. Finally, the prepared sample was inserted into the cell holder, and absorbance of the solution was measured.
For fluoride (F−), the spectrophotometer was adjusted at 190 nm, and 2.0 ml of SPANDS reagent was added to a square sample cell filled with 10 ml water. It was left for the reaction to take place, and absorbance was measured after the completion of the reaction. Similarly, ammonia, phosphate, sulfate, copper, and iron levels were determined by adjusting the spectrophotometer at 343 nm, 490 nm, 680 nm, 135 nm, and 265 nm, respectively. Ammonia salicylate reagent, PhosVer 3 phosphate reagent, SulfaVer 4 sulfate reagent, CuVer 3 copper reagents, and FerroVer iron reagent were the respective reagents used for the analysis. All the parameters were analyzed as described in standard methods.
Bacteriological analyses of water samples were done according to the procedure given by the WHO [
The level of some physicochemical parameters of the analyzed water samples are given in Tables
Level of simple physicochemical parameters of the analyzed water samples of the sampling sites.
S.P. | Turbidity (NTU) | pH | TDS (mg/l) | EC ( | |
---|---|---|---|---|---|
SW1 | 16.2 | 3.2 | 8.5 | 82 | 165 |
SW2 | 20.1 | 5.0 | 6.5 | 37 | 74 |
SW3 | 19.6 | 5.6 | 6.8 | 65 | 129 |
SW4 | 19.0 | 5.0 | 8.4 | 83 | 164 |
SW5 | 15.9 | 4.0 | 6.85 | 70 | 140 |
SW6 | 16.0 | 2.8 | 8.1 | 71 | 135 |
SW7 | 18.5 | 4.0 | 6.8 | 26 | 54 |
SW8 | 15.0 | 4.3 | 8.2 | 53 | 101 |
DW1 | 25.6 | 34.0 | 7.46 | 129 | 257 |
DW2 | 22.3 | 12.0 | 7.01 | 152 | 304 |
DW3 | 20.8 | 8.0 | 6.3 | 64 | 127 |
DW4 | 21.1 | 9.4 | 5.89 | 22 | 44 |
DW5 | 19.1 | 4.5 | 6.0 | 26 | 54 |
DW6 | 21.0 | 7.8 | 5.9 | 34 | 67 |
DW7 | 22.0 | 22.0 | 7.5 | 100 | 201 |
DW8 | 20.3 | 8.0 | 7.22 | 115 | 253 |
DW9 | 20.0 | 6.0 | 6.8 | 40 | 100 |
DW10 | 18.7 | 7.4 | 6.91 | 11 | 34 |
DW11 | 18.0 | 3.5 | 6.88 | 15 | 43 |
DW12 | 18.1 | 6.5 | 7.45 | 44 | 51 |
DS1 | 18.7 | 6.7 | 6.03 | 28 | 56 |
DS2 | 18.1 | 5.5 | 6.6 | 69 | 139 |
DS3 | 19.5 | 2.45 | 6.1 | 26 | 51 |
DS4 | 18.0 | 5.5 | 7.2 | 14 | 45 |
DS5 | 19.1 | 4.5 | 7.4 | 44 | 109 |
DS6 | 18.2 | 1.55 | 7.0 | 14 | 41 |
S.P., sampling points; SW, shallow well; DW, deep well; DS, developed springs.
Level of some chemical parameters of the analyzed water samples of the sampling sites.
S.P. | Nitrate (mg/l) | Fluoride (mg/l) | Ammonia (mg/l) | SO4−2 (mg/l) | PO4−3 (mg/l) |
---|---|---|---|---|---|
SW1 | 7.6 | 0.1 | 0.8 | 3.0 | 0.32 |
SW2 | 4.8 | 0.01 | 1.3 | 12.0 | 2.3 |
SW3 | 6.7 | 0.01 | 0.46 | 8.0 | 0.43 |
SW4 | 5.9 | 0.01 | 0.54 | 9.0 | 0.4 |
SW5 | 4.9 | 0.01 | 0.53 | 11.0 | 0.34 |
SW6 | 4.61 | 0.009 | 0.38 | 4.5 | 0.14 |
SW7 | 3.6 | 0.098 | 0.4 | 2.1 | 0.12 |
SW8 | 3.9 | 0.007 | 0.8 | 6.5 | 1.1 |
DW1 | 17.8 | 0.01 | 0.9 | 5.0 | 1.2 |
DW2 | 27.8 | 0.002 | 1.4 | 15.0 | 1.1 |
DW3 | 19.2 | 0.01 | 1.4 | 10.0 | 0.9 |
DW4 | 26.7 | 0.01 | 1.2 | 11.0 | 1.1 |
DW5 | 24.5 | 0.012 | 0.9 | 12.0 | 1.2 |
DW6 | 31.7 | 0.011 | 2.4 | ND | 1.31 |
DW7 | 10.0 | 0.0079 | 0.5 | 4.6 | 0.14 |
DW8 | 12.0 | 0.0071 | 0.82 | 3.0 | 0.6 |
DW9 | 10.5 | 0.0072 | 0.80 | 8.0 | 0.51 |
DW10 | 11.2 | 0.0069 | 0.6 | 7.0 | 0.38 |
DW11 | 11.0 | 0.0099 | 0.51 | 7.5 | 0.5 |
DW12 | 15.7 | 0.0089 | 1.5 | 7.1 | 0.5 |
DS1 | 19.7 | 0.01 | 1.2 | 5.0 | 1.6 |
DS2 | 20.6 | 0.02 | 1.1 | 8.0 | 1.8 |
DS3 | 23.4 | 0.012 | 1.5 | 3.0 | 1.3 |
DS4 | 10.7 | 0.0017 | 0.55 | 4.0 | 1.0 |
DS5 | 11.0 | 0.0091 | 0.5 | 5.0 | 1.12 |
DS6 | 11.2 | 0.0099 | 0.85 | 2.2 | 0.91 |
Temperature measurements are very useful in understanding the trend of physical, chemical, and biological activities which are enhanced/retarded by the variation of temperature. In the present study, the temperature of the water samples varied from 15.0 to 25.6°C (Table
The control of turbidity is one of the indicators of the efficiency of treatment at the plant. The scattering of light increases as the presence of suspended load increases, and turbidity is commonly measured in nephelometric turbidity units (NTU). Elevated levels of turbidity in the treated water indicate that the treatment process is not operating adequately. It also provides a good indication of whether the treatment plant is capable of removing
The pH which depends on carbon dioxide and carbonate-bicarbonate equilibrium is an important indicator of water quality. The pH is an important variable in water quality assessment as it influences many biological and chemical processes within a water body and all processes associated with water supply and treatment. Dial variations in pH can be caused by the photosynthesis and respiration cycles of algae in eutrophic waters. The pH of most natural waters is between 6.0 and 8.5, although lower values can occur in dilute waters high in organic content and higher values in eutrophic waters, ground water brines, and salt lakes [
In drinking water, total dissolved solids are primarily made up of inorganic salts with small concentrations of organic matter. Contributory ions are mainly carbonate, bicarbonate, chloride, sulfate, nitrate, potassium, calcium, and magnesium. A major contribution to total dissolved solids in water is due to the natural contact with rocks and soil. Total dissolved solids in drinking water originated from natural sources, sewage, urban runoff, and industrial wastewater [
Electrical conductivity in water is the measurement of the ability of a solution to carry an electrical current. This ability depends on the presence of ions, their total concentrations, mobility, and on the temperature of measurements [
Fluoride concentrations of 0.7–1.2 mg/l in drinking water will protect against dental cavities. However, excessive levels (more than 1.5 mg/l) may cause discoloration or mottling of the teeth. This occurs only in developing teeth before they push through. Elevated fluoride levels also may cause skeletal damage and bone disease. Because low levels of fluoride are common in groundwater, most municipalities add fluoride to the water. The fluoride contents of the water samples in the current study were in the range 0.0017 mg/l (DS4) to 0.1 mg/l (SW1) (Table
Nitrate is a compound of nitrogen and oxygen that is found in many ways. The groundwater has high nitrate concentration than surface water because of the percolating sewage, industrial waste, chemical fertilizers, leaches from solid waste landfills, and septic tank effluents to the groundwater. The nitrate concentration in surface and groundwater is normally low but can reach high levels as a result of leaching or runoff from agricultural land or contamination from human and animal wastes [
Sulfate is an abundant ion in the earth crust, and its concentration in water range from few to several milligrams per liter [
Phosphates in water mostly originated from sewage effluents, which contain phosphate-based synthetic detergents, from industrial effluents or from land runoff where inorganic fertilizers have been used in farming. Phosphate is a major source of concern for surface waters because small amounts may lead to eutrophication of lakes and rivers. Historically, phosphate was not considered to be a significant problem in groundwater because it is not very mobile in soils or sediments and should therefore be retained in the soil zone. However, in extremely vulnerable areas, where the soil and subsoil are shallow and where phosphate enters groundwater in significant quantities, it may act as an additional nutrient enrichment pathway for receptors such as lakes, rivers, and wetlands. The maximum allowed concentration for phosphorus in drinking water is 5 mg/l as P2O5, equivalent to 2.2 mg/l P (SI No. 81 of 1988). This is well above natural levels and an annual median phosphate concentration of 0.03 mg/l P is cited as a limit (to prevent eutrophication in surface waters) in phosphate regulations [
USEPA makes the following recommendations [
Ammonium in water supplies originates from agricultural and industrial processes, as well as from disinfection with chloramines (a method of disinfection not in use in Ireland). Elevated levels of ammonium may arise from intensive agriculture in the catchment of the water source. Ammonium is therefore an indicator of possible bacterial, sewage, and animal waste pollution. Ammonium in itself is not a health risk, but the parametric value serves as a valuable indicator of source pollution. The parametric value of ammonium as stated by EPA is 0.3 mg/l, and its permissible limit recommended by the WHO and CES is 1.5 mg/l. The level of ammonia in the water samples of the current study varied from 0.38–2.4 mg/l. While the ammonia level of 100% of the studied samples violated the guideline set by EPA, only one sample (DW6) crossed the WHO and CES guideline of drinking water quality. The ammonia level of the water samples from the kebeles in Koga irrigation is higher than the ammonia level of the samples from the study sites out of the irrigation site. This relatively higher ammonia content of the water samples may be due to agriculture fertilizers used in Koga irrigation found near the area. High levels of ammonia are usually due to agricultural, sewage, and metabolic processes in the ground [
To estimate the level of trace metals, the copper and iron levels of drinking water samples from the study area were measured (Table
Copper and iron contents of the studied water samples of the study sites.
Sampling points | Copper (mg/l) | Iron (mg/l) |
---|---|---|
SW1 | 0.03 | 0.05 |
SW2 | ND | 0.37 |
SW3 | ND | 0.2 |
SW4 | 0.02 | ND |
SW5 | 0.32 | 0.3 |
SW6 | 0.01 | 0.03 |
SW7 | ND | 0.27 |
SW8 | ND | 0.11 |
DW1 | 0.33 | 0.27 |
DW2 | 0.02 | 0.7 |
DW3 | 0.1 | ND |
DW4 | ND | 0.48 |
DW5 | ND | 0.65 |
DW6 | 0.01 | 0.4 |
DW7 | 0.01 | ND |
DW8 | 0.21 | ND |
DW9 | ND | 0.33 |
DW10 | ND | 0.28 |
DW11 | 0.01 | 0.18 |
DW12 | 0.001 | 0.15 |
DS1 | 0.02 | 0.04 |
DS2 | 0.01 | 0.03 |
DS3 | 0.01 | 0.06 |
DS4 | 0.002 | 0.02 |
DS5 | 0.001 | 0.01 |
DS6 | 0.01 | 0.03 |
ND, not detected.
Copper is a nutrient essential for health, though at elevated levels can become a contaminant (elevated levels can cause acute gastrointestinal effects). The primary source of copper in drinking water is from corrosion of internal copper plumbing. The levels of copper in drinking water depend on the length of time the water has been stagnant in the copper piping, and thus, fully flushed water generally has low levels of copper. The levels of contamination can be increased near smelting facilities and phosphate fertilizer plants. In the study area, the concentration of copper ranged from nil to 0.33 mg/l (Table
Iron is an abundant metal found in earth’s crust. It is naturally present in water but can also be present in drinking water from the use of iron coagulants or the corrosion of steel and cast iron pipes during water distribution. Iron is an essential element in human nutrition. The WHO [
The term “faecal coliform” has been used in water microbiology to denote coliform organisms which grow at 44 or 44.5°C and ferment lactose to produce acid and gas. In practice, some organisms with these characteristics may not be of faecal origin and the term “thermotolerant coliform” is, therefore, more correct and is becoming more commonly used. Nevertheless, the presence of thermotolerant coliforms nearly always indicates faecal contamination. Usually, more than 95% of thermotolerant coliforms isolated from water are the gut organism
The total coliform count of the studied water samples was in the range from 0 (nil) to 200 cfu/100 ml (Table
The total coliform count of the studied water samples for the study sites.
Sampling points | Thermotolerant count |
---|---|
SW1 | ND |
SW2 | 25 |
SW3 | 22 |
SW4 | 10 |
SW5 | ND |
SW6 | 15 |
SW7 | 20 |
SW8 | 25 |
DW1 | 200 |
DW2 | 150 |
DW3 | 100 |
DW4 | 165 |
DW5 | 12 |
DW6 | 142 |
DW7 | 185 |
DW8 | 200 |
DW9 | 160 |
DW10 | 145 |
DW11 | 140 |
DW12 | 28 |
DS1 | 6 |
DS2 | 5 |
DS3 | 12 |
DS4 | 9 |
DS5 | 7 |
DS6 | 4 |
The turbidities of 100% of the studied water samples crossed the EPA limits of drinking water; the pH values for 23.08% of the analyzed water samples were not within the safe limit of standard set by the WHO and Ethiopian drinking water guidelines; the ammonia level of 100% of the studied samples violated the guideline set by EPA (may be due to agriculture fertilizers used in Koga irrigation found in the study area); the phosphate concentration of the studied water samples was above the phosphate regulations limit of EPA; and the iron level for 38.46% of the water samples had surpassed the parametric value given by EPA. The PO4-P (mg/l) level of all analyzed water samples had exceeded the maximum acceptable level of 0.10 mg/l PO4-P for prevention of eutrophication. This is an indication of significant anthropogenic inputs from domestic sewage, agricultural, and use of phosphate detergents. It follows that virtually all the water points in these regions are already under hypereutrophic state.
The total coliform number of most studied water samples (except sites SW1 and SW5) exceeded the upper limit set for drinking water bodies. This study concluded that the water sources of the study area are not safe for drinking unless appropriate treatment measurements are taken. The values for the water quality parameters for the water samples collected from Koga irrigation site were higher than the values for the water samples from the study sites found out of the irrigation site. This indicated the pollution load of Koga irrigation on the water quality of the area. The drinking water from the groundwater well was above the WHO standard for turbidity and well above the recommended bacteria levels. The water source is probably contaminated. Therefore, the municipal administration and service rendering sectors should provide the wastewater treatment in order to reduce the pollutants entering into the water points of the study areas. Further research should be conducted in the water points to investigate the detail water quality status of the areas by considering the seasonal/temporal variations of the water quality parameters throughout the year. Since, the current research is only limited to one season (dry season).
The data used to support the findings of this study are available from the corresponding author upon request.
The author declares that there are no conflicts of interest.