Assessment of the potability and carcinogenic and non-carcinogenic health risks of drinking water in rural areas of the Amhara region, Ethiopia

Water, constituting 70% of the Earth's crust, is the paramount essential resource for life in urban and rural areas, playing a crucial role in the survival of living organisms (Gillani et al. 2013). However, access to clean water has become a global challenge, particularly in developing countries, including Ethiopia. As of 2022, 2.2 billion people were without access to safely managed drinking water. In rural areas, four out of five people lack access to safe drinking water (UNICEF/WHO 2023). Over 1.7 billion people lack access to basic sanitation facilities, with 709 million residing in sub-Saharan Africa (WHO 2019). Around two-thirds of urban residents in low-income countries, primarily in Africa, face severe water quality and sanitation challenges (UNESCO 2019). According to UNEP (2021), over 3 billion people in low- and middle-income countries could be at risk because their freshwater ecosystems' health status is below standards. Sukri et al. (2023) reported that coastal communities utilize tidal water sources that do not meet clean water standards, significantly affecting the well-being of the communities.

Among sub-Saharan countries, Ethiopia has the lowest access rate to safe drinking water (Siraj & Rao 2016). Despite its vast water resource potential, the country struggles with limited access to safe drinking water and adequate sanitation services (WHO 2006; Demie et al. 2016). Frequent interruptions in the piped water supply often lead to prolonged drinking water storage, resulting in significant contamination (Adane et al. 2017; Chalchisa et al. 2018). According to the Ethiopian demographic and health survey report, people in different regions were exposed to various diseases due to water contamination and poor sanitation (CSA 2016). Various studies across the country indicate that drinking water becomes chemically and bacteriologically contaminated from the source to households. As a result, drinking water in many parts of Ethiopia fails to meet WHO's prescribed standards (Siraj & Rao 2016; Usman et al. 2016; Asefa et al. 2021).

The consumption of non-conventional water poses significant public health concerns, with an estimated 80–85% of communicable waterborne diseases. For instance, potentially harmful metals (PHMs), elements with a density exceeding 4,000 kg/m³ and five times greater density than groundwater, contribute to the deterioration of water quality (Amini Birami et al. 2020). The consumption of moderate to low concentrations of PHMs such as chromium (Cr), arsenic (As), nickel (Ni), cadmium (Cd), manganese (Mn), lead (Pb), zinc (Zn), cobalt (Co), copper (Cu), mercury (Hg), and iron (Fe) induces adverse health effects including hearing loss, disabilities, growth inhibition, gastrointestinal diseases, sleep disorders, irritability, constipation, fatigue, and cramps (Rashid et al. 2019a,b). Although metals such as Zn, Fe, Cu, and Mn function as micronutrients and are essential for human nutrition, their elevated concentration poses toxicity risks when consumed by humans (Kalyoncu et al. 2012). Children consuming water with heightened concentrations of Pb can be exposed to severe neurological damage, coma, convulsions, organ failure, and, ultimately, death (Singh et al. 2018). Boyd (2006) stated that among the contaminants in drinking water, microbiological pathogens pose the most significant and essential risk. Generally, the lack of reliable and safe water sources perpetuates a cycle of poverty, hindering economic growth and stifling the potential for social progress.

The geochemical, biological, and anthropogenic activities deteriorate water quality. Population growth and rapid urbanization are among the factors intensifying pressure on freshwater resources, leading to the contamination of drinking water. Over the past two to three decades, there has been a notable rise in industrialization, urbanization, population density, and the consumption of natural resources, accompanied by increased mining activities. Consequently, there is an increase in pathogenic, chemical, and radiological water contaminants, leading to the deterioration of water quality (WHO/UNICEF 2008). Moreover, nutrients and agrochemicals utilized in cultivation areas near water bodies reach surface water bodies through overland and subsurface flows during precipitation events, or gradually through groundwater discharge (Johannsen & Armitage 2010). Due to this, the availability of clean water resources has declined globally (Ponsadailakshmi et al. 2018; Rashid et al. 2019a,b). As a result, people have been prompted to utilize untreated non-conventional water sources such as deep wells (DWs) and shallow wells (SWs) (Javier & Jacob 2015). Therefore, managing water sources using nature-based solutions and fostering community interaction is crucial to guaranteeing water supply, fulfilling the community's needs, and achieving sustainable development (Díaz et al. 2020).

The type of pollutants and degree of water pollution vary from place to place depending on the people's activities and environmental conditions. Therefore, the temporal and spatial monitoring and management of drinking water quality should be emphasized to safeguard public health. Water quality is assessed based on physical, chemical, biological, and esthetic characteristics. Safe drinking water should ideally be free of pathogens, have low concentrations of toxic chemicals, and be clear, tasteless, and colorless for esthetic purposes (Lukubye & Andama 2017; WHO 2024). The WHO recommends drinking water with turbidity below 5 NTU, and the absence of fecal (FC) and total coliform (TC) in 100 mL of drinking water as their presence suggests the potential presence of pathogenic bacteria (WHO 2015; UNICEF/WHO 2023). Microbial or chemical contamination, imperceptible to the senses of sight, smell, or taste, can only be identified through laboratory testing. Comprehensive testing for all potential microbial pathogens remains challenging. As a practical approach, testing common indicators such as TC, FC, and Escherichia coli bacteria is conducted to assess water quality (Wagner & Lanoix 1969).

In the current study areas, namely Gutera, Melina, and Yetenib kebeles found in Enemay Woreda, Amhara Region Ethiopia, only 12% of the total population (192,292 individuals) have access to drinking water from protected areas. The remaining population relies on unprotected sources such as river water, including dam canals for irrigation (Enemay Woreda Office of Water 2022). The three kebeles exhibit four water points: reservoirs, DWs, developed springs (DSs), and SWs. All drinking water sources in the study areas do not have pollutant prevention measures. Consequently, wastes from animals, human excretes, agricultural runoff, and domestic activities easily enter the drinking water sources, rendering the water potentially polluted and unfit for drinking. Therefore, temporal and spatial monitoring of drinking water quality is crucial to protect people from waterborne diseases. However, no former studies have been conducted on the quality and the carcinogenic and non-carcinogenic health risks associated with the ingestion of heavy metals through drinking water in the study area.

Therefore, the objective of this study was to evaluate the potability and carcinogenic and non-carcinogenic risk of drinking water in rural areas of the Amhara Region, Ethiopia. The results of this study can play a vital role in (1) safeguarding public health, (2) enhancing environmental protection, (3) developing guidelines, (4) addressing water pollutants, and (5) promoting sustainable development and informing policy-making, leading to improved regulatory standards and sustainable water management practices, and (6) providing literature sources for future researches.

The equipment, the chemicals, and the standard procedures of water quality analysis mentioned by Lewoyehu (2021) were also used during the laboratory analysis of this study. pH meter (Hana portable pH meter, Germany), EC meter (DDB-11A portable conductivity meter), volumetric flask (25–1,000 mL), filter paper (Whatman no. 1), dropper (0.5–1 mL), sample cells (1-inch square, 10 mL), nephelometric turbidometer, sample bottle, hand lens, vacuum pump, Palintest test tube, and photometer (Palintest Photometer 8000, UK) are among the equipment used for the accomplishment of the research (Lewoyehu et al. 2022).

Nitric acid (HNO₃ (69–72%)), Palintest phosphate, HR tablets, SR tablets, H₂SO₄ (98%), buffer solutions (pH 4, 7, and 9), NitraVer 5 nitrate reagent, ChloroVer reagent, PhosVer 3 phosphate reagent, SulfaVer 4 sulfate reagent, and membrane lauryl sulfate broth (ACM-1820-O) are among the analytical grade chemicals used in the research (Lewoyehu et al. 2022). Distilled water was used throughout the research.

Three study sites, namely Yetenibina Weyinam (Yetenib), Debrie Gutera (Gutera), and Debre Genet Melina (Melina), were selected considering the pollution load from human and animal excretes, leachates of chemical fertilizers, and agrochemicals. Details of the sampling sites and their GPS coordinates are presented in Table 2. Before sampling, all sampling materials underwent a rigorous cleaning. This involved washing with detergent, rinsing with distilled water, soaking in 10% nitric acid (HNO₃) for 24 h, re-rinsing with deionized water, and air-drying, as per the guidelines outlined by the Ministry of Health (MOH 2011). In January 2022, 12 composite water samples were collected from various drinking water sources used by the dwellers: six from DWs – two from each kebele, three from SWs – one from each kebele, and three from DSs – one from each kebele. To obtain composite water samples of each drinking water source at each sampling site, water samples were taken from three different points of each site using 250 mL polyethylene bottles. These samples were then combined into a 1-L polyethylene containing 2 mL of 5% HNO₃ to prevent metal adsorption by the bottle walls (APHA 2012). The containers were then labeled with the sampling date and site. Water pH, electrical conductivity (EC), turbidity, and total dissolved solids (TDS) were measured in situ employing the procedures outlined by the WHO (2017). For laboratory analysis, the samples were transported in an ice box and refrigerated at 4 °C until chemical analyses were carried out. For bacteriological analysis, distinct bottles and ice boxes were used to collect water samples, and the analysis was conducted within 24 h of sample collection.

EC, TDS, turbidity, and pH were measured in situ after calibrating a portable conductivity meter, TDS meter, turbidometer, and pH meter, respectively (Lewoyehu 2021; Lewoyehu et al. 2022). The pH meter was calibrated using acidic, neutral, and basic buffer solutions with pH values of 4, 7, and 9, respectively. The EC meter was calibrated using standard solutions of KCl with conductivities of 1,413 and 84 μS/cm. The turbidometer was calibrated using prepared standards following the manufacturer's operating instructions. Then, a 10 mL water sample was taken in cuvettes and readings were recorded in nephelometric turbidity units (NTU). TA, TH, ⁠, ⁠, ⁠, ⁠, Ca²⁺, and Mg²⁺ were calorimetrically determined using a Palintest transmittance display photometer (Model DR-2800), following the manufacturer's instructions. Na⁺ and K⁺ were determined using a flame photometer (Model FP640). To determine ⁠, ⁠, and ⁠, SulfaVer 4 sulfate reagent, PhosVer 3 phosphate reagents, and NitraVer 5 nitrate reagent powder pillow were added to separate sample cells, each filled with 10 mL water. After allowing for the reaction to occur, absorbance was measured. To determine TA, a 10 mL water sample in a conical flask was titrated with 0.1 M HCl until the color turned pink, using methyl red as an indicator (Lewoyehu 2021; Lewoyehu et al. 2022).

TC and FC were measured using the membrane filtration method (WHO 2004). TC was identified through growth in a medium containing lactose at a temperature of 35─37 °C based on acid and gas production from lactose fermentation. FC was measured by filtering 100 mL of water through a 0.45 μm membrane filter. Bacteria were retained on the surface of filter paper placed on a suitably prepared medium and incubated at 44.5 °C for 24°h. The resulting yellow colonies of thermotolerant or FC were directly counted using a hand lens. The concentrations of Mn, Cu, As, Pb, and Cd in the water samples were measured using ICP-OES under the specified operating conditions.

The Schoeller diagram was used to identify the water type of the study area based on the order of dominant cations and anions. A Gibbs scatter plot (Gibbs 1970) was used to determine the dominant factor among weathering of rocks, precipitation, and/or evaporation that affect the chemical composition and chemistry of drinking water in the study area. The GPI formulated by Subba Rao (2012) was calculated to estimate the groundwater quality. It examines the impact of specific variables on the overall quality of groundwater (Subba Rao 2017). The GPI technique has proven to be efficacious in monitoring the quality of drinking water in diverse locations (Rao et al. 2018). The computation of the GPI involves five steps (Subba Rao 2017, 2018).

• I. Assigning relative weight (Rw): This is based on two main factors, the importance of the parameters in determining the overall quality of groundwater and its relative impact on human health. Based on Subba Rao (2012), scales from 1 to 5 were used with the lower end being 1 for K⁺, 2 for Ca²⁺ and Mg²⁺, 3 for turbidity, and ⁠, 4 for pH, EC, TDS, TH, Na⁺, and Mn, and 5 for ⁠, ⁠, and Cl⁻ (Table 3).

• II. Calculating weight parameter (Wp): It is the ratio of Rw of every water quality measure to the sum of all relative weights.

  

  (1)
• III. Computation of status of concentration (Sc): This is computed by dividing the concentration (C) of each water quality measure of every water sample by its respective drinking water quality standard (Ds).

  

  (2)
• IV. Calculating the overall water quality (OW): This reflects the overall water quality and it enables us to understand the nature of the weight parameter with respect to the concentration of each water quality measure.

  

  (3)
• V. Calculating GPI and classification:

  

  (4)

Table 3

Scheme for assigning weights to water quality measures in the context of drinking water standards

Parameter .	Unit .	Rw .	Wp .	Ds WHO (2006, 2011)  .
Turbidity	NTU	3	0.056604	5
pH	–	4	0.075472	7.5
EC	μS/cm	4	0.075472	500
TDS	mg/L	4	0.075472	500
TH	mg/L	4	0.075472	300
	mg/L	3	0.056604	0.03
	mg/L	5	0.09434	250
	mg/L	5	0.09434	50
Cl−	mg/L	5	0.09434	250
	mg/L	3	0.056604	200
Na+	mg/L	4	0.075472	200
K+	mg/L	1	0.018868	10
Ca2+	mg/L	2	0.037736	75
Mg2+	mg/L	2	0.037736	50
Mn	mg/L	4	0.075472	0.5
Sum		53	1.0

Parameter .	Unit .	Rw .	Wp .	Ds WHO (2006, 2011)  .
Turbidity	NTU	3	0.056604	5
pH	–	4	0.075472	7.5
EC	μS/cm	4	0.075472	500
TDS	mg/L	4	0.075472	500
TH	mg/L	4	0.075472	300
	mg/L	3	0.056604	0.03
	mg/L	5	0.09434	250
	mg/L	5	0.09434	50
Cl−	mg/L	5	0.09434	250
	mg/L	3	0.056604	200
Na+	mg/L	4	0.075472	200
K+	mg/L	1	0.018868	10
Ca2+	mg/L	2	0.037736	75
Mg2+	mg/L	2	0.037736	50
Mn	mg/L	4	0.075472	0.5
Sum		53	1.0

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If GPI < 1, it indicates insignificant pollution; 1.0 < GPI < 1.5 implies low pollution; 1.5 < GPI < 2 implies moderate pollution; 2 < GPI < 2.5 implies high pollution, and GPI > 2.5 indicates very high pollution.

Human health risk due to heavy metal entry into the human body via drinking water was measured by calculating the chronic daily intake (CDI) and hazard quotient (HQ) indices for the carcinogenic risk (CR) of As and the non-CR of the heavy metals detected in the drinking water samples (Mn, Cd, and Cu). Based on the reported literature, children with an average body weight of 12 kg and daily average water intake of 1 L, and adults with an average body weight of 72 kg and daily average water intake capacity of 2 L, were considered for the assessment.

The exposed population is assumed to be safe from non-cancer health risks when HQ < 1, and HQ > 1 is considered as long-term non-cancer health hazard effects of heavy metals on human health (Singh et al. 2018). All values except the metal concentration were obtained from the US EPA database for two individual population groups (children and adults) for the calculation of risk assessment (US EPA 1991, 2002, 2010).

Accordingly, the ICBE, calculated using the major cations (Na⁺, K⁺, Ca²⁺, and Mg²⁺) and anions (⁠⁠, ⁠, ⁠, Cl⁻, and ⁠), ranged from 0.005 to 3.92% (ICBE < 5%) for the drinking water samples of all sites, indicating the accuracy of the analytical data.

All water quality data were subjected to analysis using Microsoft Excel 2019, and descriptive statistics were employed to analyze the data, expressing the results as mean ± SD (standard deviation) of triplicate measurements. The software statistical package for social science (SPSS version 22, IBM Inc., Armonk, NY, USA) was used for statistical analysis of data. A one-way analysis of variance was used to test the significant differences in water pH, turbidity, EC, TDS, TA, TH, ⁠, ⁠, ⁠, Cl⁻, ⁠, TC, FC, and trace and heavy metal contents of the water samples from different sites. Significant differences in the water quality parameters were determined using the least significant difference with the Tukey post hoc multiple comparisons test (Tukey 1994) at P < 0.05. Pearson correlation analysis was done among the water quality parameters. Origin software (OriginPro 2018) was used to generate Gibbs plots and the calibration curves for the analyzed metals.

EC is an indirect measure of the ion concentration and salinity of water, signifying the presence of total dissolved salts (WHO 2022). It is a valuable indicator for assessing water purity (Acharya et al. 2008). A comparison of EC levels across sampling sites revealed that SW₂ samples exhibited the lowest EC (382.33 ± 2.08 μS/cm), while the highest EC level was recorded at DW_2A (928.33 ± 7.63 μS/cm), resulting in an average value of 534.41 ± 190.11 μS/cm (Table 4). According to the WHO, the United States Public Health Service (USPHS), and ECS standards, the maximum permissible EC level of drinking water is 300, 300, and 1,000 μS/cm, respectively. In this study, EC values of the water samples fell within the range of 382.33–928.33 μS/cm, indicating that the EC of the water samples from all sampling sites surpassed the WHO and the USPHS threshold limit but not the ECS. Therefore, based on the WHO and the USPHS standards, the studied water samples were not found to be potable for drinking as the EC level crossed the maximum allowable limit.

TDS represents a numerical expression of the concentration of filterable solids present in water, comprising organic salts and dissolved materials (McCleskey et al. 2023). Salts in natural waters consist of anions such as carbonates, chlorides, sulfates, and nitrates (predominantly in groundwater), and cations such as potassium, magnesium, calcium, and sodium. The TDS levels in the current drinking water samples varied from 244.69 ± 1.33 mg/L (SW₂) to 621.98 ± 5.11 mg/L (DW_2A). Mean values demonstrated a significant difference (P < 0.05), with the value at DW_2A being the highest (Table 4). According to the WHO (2006), the desirable limit for TDS is 500 mg/L, and the maximum limit prescribed for drinking water is 1,000 mg/L. Consequently, the TDS levels in the water samples at DW_2A and DW_2B exceeded the desirable limit suggested by the WHO, as well as the recommended limits of ECS and USPHS, 500 mg/L. Pham & Nguyen (2024) reported a TDS concentration of 588–2,153 mg/L for the groundwater at the landfill and salt-affected area of Ca Mau Province, Vietnam.

TH represents the combined concentrations of calcium and magnesium in carbonate forms measured in milligrams per liter (Duressa et al. 2019). The mean TH of the water samples ranged from 181.33 ± 1.52 mg/L (SW₂) to 691.00 ± 1.00 mg/L (DW_2B), exhibiting a significant difference (P < 0.05) among the sampling sites, with DW_2B registering higher levels than other sites. Based on the US EPA (2000), the hardness levels of human drinking water are categorized as soft (0–75 mg/L), moderately hard (75–150 mg/L), hard (150–300 mg/L), and very hard (>300 mg/L). According to this classification, the drinking water samples at SW₃, DW_2A, DW_2B, DW_3A, and DW_3B were categorized under very hard water, while others fell under moderately hard water. According to WHO recommendations, the most desirable level of TH in drinking water is 100 mg/L, although levels up to 300 mg/L may not be significantly problematic. The ECS recommends a TH level of 300 mg/L for drinking water, while the USPHS sets a maximum TH level of 250 mg/L. Based on these standards, the TH levels of drinking water samples at SW₃, DW_2A, DW_2B, DW_3A, and DW_3B exceeded the optimum level. The causes for the higher TH level of the water samples could be associated with fertilizers and soil amendments used in agriculture, which can contribute to water hardness (UNICEF/WHO 2023). Some fertilizers and agrochemicals contain calcium and magnesium compounds, which can leach into the groundwater or surface water supplies. Additionally, groundwater tends to have higher mineral content because it has been in contact with soil and rocks for longer periods, dissolving more minerals as it moves through the earth.

The excessive concentration of in water affects human health causing several diseases, such as diarrhea, dehydration, and gastrointestinal disorders (Man et al. 2014). Due to this, the ECS, WHO, BIS, and China's Sanitary Standard for drinking water quality set a limit on sulfate concentration, restricting it to less than 250 mg/L. The primary sources of sulfate pollution are categorized into several key areas: atmospheric deposition, soil, fertilizers, evaporite deposits, sulfide minerals, detergents, and coal (Wang & Zhang 2019). Zak et al. (2020) identified natural sources of dissolved SO₄²⁻ in freshwater, such as mineral weathering, volcanic activity, organic matter decomposition, sulfide oxidation, and sea spray. They also highlighted that anthropogenic sources, including acid mine drainage, fertilizer leaching, wetland drainage, and industrial runoff, contribute 20–90% of sulfate loads in surface waters. In our study, the concentration in the drinking water samples ranged from 31.9 at DS₁ to 46.92 mg/L at DS₂, with mean values showing significant differences (P < 0.05) among different sites. This indicated that the sulfate content in the studied water samples remained below the threshold level of 250 mg/L, preventing surface water pollution. Similarly, Hong & Nguyen (2023) reported low sulfate concentration (27.47–30.52 mg/L) for the surface water in the Mekong Delta, Vietnam. The levels ranged from 3.33 mg/L (DS₁) to 30.36 mg/L (SW₂), with significant variations (P < 0.05) among the sampling sites. The maximum allowable limit of in human drinking water set by the ECS, the WHO, and the USPHS is 50 mg/L. Hence, water in the study area is considered safe in terms of content for drinking and other domestic uses. Rashid et al. (2019a,b) observed that the levels of EC, turbidity, ⁠, and in groundwater and surface water samples from District Chitral, Northern Pakistan, surpassed the guideline limits set by the WHO. The chloride (Cl⁻) levels in the analyzed drinking water samples ranged from 4.4 mg/L at SW₁ to 21.31 mg/L at DS₂, exhibiting significant differences in mean values among different sites. Importantly, the Cl⁻ levels in the studied water samples remained below the WHO and ECS threshold of 250 mg/L. is an essential component of the carbonate system, providing natural water with buffer capacity and contributing to its alkalinity (Kerr et al. 2021). In this study, the concentration varied from 177.59 mg/L at DS₁ to 360.5 mg/L at DW_3B with an average of 364.64 mg/L. The level of all water samples except DW_3B surpassed the WHO limit (200 mg/L), which could contribute to the water's hardness when it undergoes chemical reactions with Ca²⁺ or Mg²⁺ and forms carbonates of calcium or magnesium. The higher proportions of bicarbonate over other anions reflect the weathering of primary silicate minerals and carbonates, which tend to enrich bicarbonate (Mwiathi et al. 2022).

The bacteriological and trace and heavy metal contents of the analyzed water samples are depicted in Table 5.

The TC and FC of the studied water samples ranged from 18.00 ± 1.00 and 6.66 ± 0.57 cfu/100 mL at SW₃ to 1,798 ± 17.55 and 298.00 ± 8.18 cfu/100 mL at DW_1A, respectively, with significant variations of the samples from different sites (Table 5). The allowable TC and FC for drinking water set by the Environmental Protection Agency (EPA), WHO, and ECS is 0 cfu/100 mL. Therefore, the bacterial colony counts in drinking water samples from all sampling sites exceeded the WHO, EPA, and ECS drinking water quality guideline limit. This demonstrated that there was fecal pollution in the drinking water sources of the sampling sites as people in the sampling area did not have properly constructed toilets, and hence, both human and animal excretes easily entered the drinking water sources. According to Michael's classification (Michael 2006), DW and SW water with TC and FC levels of 1–10 cfu/100 mL pose low risk, 11–100 cfu/100 mL cause intermediate risk, 101–1,000 cfu/100 mL cause high risk, and >1,000 cfu/100 mL can pose very high risk. Based on this classification, water samples at DW_1A, DW_1B, DW_2A, and DW_2B could induce very high risk; water samples at DW_3A and DW_3B could lead to high risk; and water samples at the remaining sites might bring an intermediate health risk. Conclusively, based on the TC and FC results of this study, none of the drinking water sources fulfilled the drinking water quality standard. This may induce diarrheal diseases via the fecal–oral route and pose potential hazards to human health. The TC values of this study were higher than the TC values reported for the drinking water in the Mecha district found in the rural part of Ethiopia, where TC values of 4–12, 0–25, and 12–200 NTU were reported for DS, SW, and DW-drinking water, respectively (Lewoyehu 2021). Similarly, Rashid et al. (2022) reported that the groundwater of the Hindukush ranges, Pakistan was found to be contaminated with coliform bacteria encompassing 80% E. coli, 70% F. coli, and 72% P. coli, showing exceedance of the WHO guideline values of 0 cfu/100 mL water for E. coli, F. coli, and P. coli (WHO 2011). Furthermore, Pant & Singh (2024) found that 100% of the surface water samples from the Rispana River in India exceeded the permissible limit for TC, and 75% of the samples were deemed unfit for drinking. Pant et al. (2024) also reported that 75% of the sampling sites in the springs of the Indian Himalayan Region were contaminated with bacterial pathogens, such as E. coli and TCs, which varied from 1 to 2,496.1 MPN/100 mL, exceeding the BIS/WHO standards' permissible limit of 0 MPN/100 mL.

The concentration of Na⁺ ranged from 16.0 mg/L at DS₂ to 20.42 mg/L at SW₂ with significant variations among the sampling sites. The level of Na⁺ in all analyzed water samples was below the threshold limit (200 mg/L) stated by the WHO and ECS. Similarly, the concentration of K⁺ in all tested water samples fell below the maximum limit (10 mg/L) recommended by the WHO and ECS, with variations from 2.10 mg/L at DW_3A to 2.92 mg/L at SW₃. Ca²⁺ and Mg²⁺ can cause water hardness if their concentration surpasses the recommended limit, 75 and 50 mg/L, respectively (WHO 2006). In this study, the level of Ca²⁺ ranged from 13.38 mg/L (DW_1A) to 51.92 mg/L (DW_2A) mg/L, with an average value of 24.26 ± 12.88 mg/L. Meanwhile, Mg²⁺ concentrations ranged from 28.12 ± 0.58 mg/L (DW_3B) to 71.27 ± 1.21 mg/L (DS₁), with an average value of 43.68 ± 12.55 mg/L (Table 5). Although the concentration of Ca²⁺ in all water samples remained below the recommended limit (75 mg/L), the Mg²⁺ concentration at DS₁, DS₂, and DS₃ exceeded the threshold limit (50 mg/L). The concentration of Mn in this study ranged from 0.040 mg/L at DW_1A to 0.222 mg/L at SW₃, with significantly varied mean values among different sites (Table 5). The maximum recommended concentration of Mn in human drinking water is 0.5 mg/L (FAO 1985; WHO 2006; ECS 2011). Thus, the Mn level in the drinking water samples from all sources was below the maximum threshold limit. According to the BIS (2016), the optimum level of Mn in drinking water is 0.1 mg/L. Hence, the water samples at DS₁, DS₂, SW₃, and DW_3B surpassed this limit.

The concentration of As in this study ranged from below the limit of detection (LOD) at DS₂, DS₃, SW₁, SW₂, SW₃, DW_1A, DW_2A, and DW_1B to 0.0597 mg/L at DS₁. The mean values of the water samples at DS1 and DS_3B significantly varied from samples at DW_2B and DW_3A (Table 5). In human drinking water, the maximum recommended concentration of As is 0.01 mg/L (WHO 2024). FAO (1996) recommends 0.5 mg/L of As in drinking water. According to the US Environmental Protection Agency (US EPA 1998), the maximum allowable limit of As in human drinking water is 0.001 mg/L. Thus, the level of As in the water samples at DS₁, DW_2B, DW_3A, and DW_3B was above the permissible limit stated by the WHO (2006) and US EPA (1998), and the concentration of As at all sampling sites was below the threshold limit given by FAO (1996). The higher concentrations of As in the regions of the water sampling sites may be due to the chemical fertilizers and other arsenic-containing agrochemicals used in agricultural activities. Some types of agricultural fertilizers and agrochemicals contain As. The leaching of chemical fertilizers and agrochemicals into the drinking water sources could be the reason for arsenic pollution. It is stated that As has no known necessary role in human or animal diet, but is toxic; a cumulative poison that is slowly excreted. It can cause nasal ulcers, damage to the kidneys, liver, and intestinal walls, and death, and is recently suspected to be a carcinogen (US EPA 1998). Thus, people who have been drinking water from DS₁, DW_2B, DW_3A, and DW_3B could be exposed to the above-mentioned health risk issues. In the study by Rashid et al. (2023), 14.2% of the tested groundwater samples in Mardan, Pakistan, exceeded the WHO limit of 0.01 mg/L.

The Cd concentration ranged from below LOD at DS₃, SW₁, SW₂, SW₃, and DW_1B to 0.0034 mg/L at DS₁, DW_2A, and DW_3B. Mean values for different sites did not show significant differences. The recommended maximum concentration of Cd is 0.003 for human drinking water (WHO 2004). Thus, the Cd concentration in the water samples at DS₁, DW_1A, DW_2A, and DW_3B crossed the threshold limit. Ingestion of water containing As, and Cd above their threshold limits can damage the heart and lungs and may induce allergies (Nasr et al. 2011). In the studied drinking water samples, Pb was not detected, and hence in the results shown in Table 5, it is labeled as ND (not detected) to indicate that the concentration of Pb in the tested drinking water samples was below the detection limit (DL) (0.042 mg/L) of the ICP-OES used for analysis. The maximum allowable concentration of Pb in human drinking water is 0.01 mg/L. A high concentration of Pb is toxic for animals, and young animals tend to be more susceptible to Pb poisoning than adults. In the present study, the concentration of Pb at all sites was very low, and hence, Pb toxicity problems may not be caused by ingestion of water from the study sites. However, it is crucial to further analyze Pb concentrations in drinking water using instruments with detection limits below 0.01 mg/L. Similarly, the concentration of Pb in most of the drinking water samples in Jigjiga City Ethiopia was very low and reported as below the DL of the instrument (0.005 mg/L) (Belew et al. 2024).

Copper is essential for humans, though at elevated levels, it is reported to elicit undesired health effects such as acute gastrointestinal effects. The level of Cu in this study ranged from below LOD to 0.069 mg/L (Table 5). It was not detected in most of the studied water samples; only water samples at DS₂ and SW₁ showed a Cu level above the DL of the ICP-OES. Water with a Cu level of less than 0.5 mg/L is essential to human health though its allowed concentration in human drinking water is 2 mg/L. Therefore, the concentration of Cu in the studied water samples was below the maximum permissible limit for human drinking water.

The correlation result displayed in Table 6 is used to determine the relationships between the water quality metrics for the tested water samples. The correlation results showed that EC and TDS, EC and TH, EC and Ca²⁺, TDS and Ca²⁺, TH and Ca²⁺, and Mg²⁺ and had a strong and direct association with correlation coefficient (r) values of 0.999, 0.9931, 0.925, 0.996, 0.918, and 0.757, respectively. Turbidity, ⁠, and Cl⁻, and ⁠, ⁠, and Cl⁻ showed a perfect positive correlation with a correlation coefficient (r) value of 1. While EC and pH, TDS and pH, and ⁠, and ⁠, Na⁺ and ⁠, Na⁺ and Mg²⁺ showed a strong and inverse correlation with correlation coefficient (r) values of −0.725, −0.723, −0.777, −0.774, −0.814, and −0.888, respectively.

Table 6

Pearson's correlation matrix among the tested quality parameters of the drinking water samples

Correlations .
Variables .	Turbidity .	pH .	EC .	TDS .	TA .	TH .	.	.	.	Cl− .	.	Na+ .	K+ .	Ca2+ .	Mg2+ .	Mn .
Turbidity	1
pH	−0.231	1
EC	0.412	−0.725**	1
TDS	0.414	−0.723**	0.999**	1
TA	0.071	−0.082	0.193	0.191	1
TH	0.405	−0.675*	0.931**	0.923**	−0.021	1
	−0.203	−0.266	−0.229	−0.226	−0.456	−0.151	1
	1.000**	−0.229	0.411	0.412	0.071	0.404	−0.204	1
	−0.205	−0.267	−0.231	−0.228	−0.455	−0.153	1.000**	−0.206	1
Cl−	1.000**	−0.229	0.411	0.413	0.072	0.404	−0.204	1.000**	−0.206	1
	0.435	−0.028	0.311	0.307	0.454	0.284	−0.777**	0.435	−0.774**	0.435	1
Na+	−0.465	−0.430	0.152	0.155	−0.150	0.105	0.670*	−0.466	0.669*	−0.466	−0.814**	1
K+	0.168	−0.561	0.631*	0.642*	0.283	0.381	−0.239	0.167	−0.241	0.168	0.069	0.281	1
Ca2+	0.421	−0.671*	0.925**	0.918**	−0.045	0.996**	−0.149	0.419	−0.150	0.419	0.301	0.081	0.383	1
Mg2+	0.315	0.383	−0.320	−0.319	0.381	−0.369	−0.555	0.316	−0.552	0.316	0.757**	−0.888**	−0.257	−0.351	1
Mn	0.480	0.304	−0.203	−0.195	−0.413	−0.175	0.056	0.480	0.054	0.479	0.069	−0.403	−0.343	−0.152	0.340	1

Correlations .
Variables .	Turbidity .	pH .	EC .	TDS .	TA .	TH .	.	.	.	Cl− .	.	Na+ .	K+ .	Ca2+ .	Mg2+ .	Mn .
Turbidity	1
pH	−0.231	1
EC	0.412	−0.725**	1
TDS	0.414	−0.723**	0.999**	1
TA	0.071	−0.082	0.193	0.191	1
TH	0.405	−0.675*	0.931**	0.923**	−0.021	1
	−0.203	−0.266	−0.229	−0.226	−0.456	−0.151	1
	1.000**	−0.229	0.411	0.412	0.071	0.404	−0.204	1
	−0.205	−0.267	−0.231	−0.228	−0.455	−0.153	1.000**	−0.206	1
Cl−	1.000**	−0.229	0.411	0.413	0.072	0.404	−0.204	1.000**	−0.206	1
	0.435	−0.028	0.311	0.307	0.454	0.284	−0.777**	0.435	−0.774**	0.435	1
Na+	−0.465	−0.430	0.152	0.155	−0.150	0.105	0.670*	−0.466	0.669*	−0.466	−0.814**	1
K+	0.168	−0.561	0.631*	0.642*	0.283	0.381	−0.239	0.167	−0.241	0.168	0.069	0.281	1
Ca2+	0.421	−0.671*	0.925**	0.918**	−0.045	0.996**	−0.149	0.419	−0.150	0.419	0.301	0.081	0.383	1
Mg2+	0.315	0.383	−0.320	−0.319	0.381	−0.369	−0.555	0.316	−0.552	0.316	0.757**	−0.888**	−0.257	−0.351	1
Mn	0.480	0.304	−0.203	−0.195	−0.413	−0.175	0.056	0.480	0.054	0.479	0.069	−0.403	−0.343	−0.152	0.340	1

Note: **Correlation is significant at the 0.01 level; *Correlation is significant at the 0.05 level (two-tailed).

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The GPI value provides an accurate depiction of the degree of groundwater pollution. The GPI values in this study ranged from 4.90 at DS₁ to 27.39 at SW₂. Based on the GPI classification (Subba Rao 2012), 100% of the drinking water samples in this study were categorized as very highly polluted (GPI > 2.5 for all water samples) (Table 7). The proportional influence of the water quality measure concentration in each water sample was considered when OW exceeded 0.1, which corresponds to 10% of the value of 1.0 for GPI. This analysis provides an understanding of the pollution impact on the groundwater system. Accordingly, the significant pollution of the water samples in the study area was contributed mainly by where the OW values of all water samples were above 0.1. EC at DW_2A, DW_2B, TH at DW_2A, DW_2B, and at DS₁ also showed OW values greater than 0.1. Thus, they contributed more to the pollution of the drinking water in the mentioned sampling sites. The remaining water quality measures with OW < 0.1 and GPI < 1 were nominal contributors to drinking water pollution in the study area. In contrast to our findings, the water quality index of the drinking water samples in the urban water supply systems of Hawassa, Ethiopia, was found in the safe limit (Mengstie et al. 2023). From 25 groundwater samples in Ca Mau Province, Vietnam, 12% were poor and 4% were very poor based on the groundwater quality index (Pham & Nguyen 2024). In the study by Rashid et al. (2023), 35.7% of the groundwater samples in Mardan Pakistan were found to be unfit for household purposes based on the water quality index values, and the rock weathering process was the dominant control for the chemical composition and chemistry of the water samples. Based on the groundwater quality index values, 50% of the examined groundwater samples in the Khanewal district of Punjab, Pakistan, were unsafe for drinking (Iqbal et al. 2021). Talpur et al. (2020) also reported that 100% of the tested groundwater samples in the aquifers of Badin district, Sindh, Pakistan, were unsuitable for drinking.

Table 7

Pollution status of the drinking water samples in the study area based on the GPI

S.P .	Turbidity (NTU) .	pH .	EC (μS/cm) .	TDS (mg/L) .	TH (mg/L) .	(mg/L) .	(mg/L) .	(mg/L) .	Cl− (mg/L) .	(mg/L) .	Na+ (mg/L) .	K+ (mg/L) .	Ca2+ (mg/L) .	Mg2+ (mg/L) .	Mn (mg/L) .	GPI .
	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	.
DS1	0.014	0.070	0.064	0.041	0.056	4.43	0.013	0.0063	0.0029	0.10	0.0062	0.0042	0.00842	0.054	0.026	4.90
DS2	0.037	0.071	0.064	0.041	0.068	10.9	0.018	0.015	0.0080	0.090	0.0060	0.0040	0.010	0.049	0.030	11.4
DS3	0.015	0.070	0.058	0.037	0.047	5.83	0.014	0.0082	0.0033	0.076	0.0068	0.0054	0.0070	0.038	0.0068	6.22
SW1	0.0077	0.070	0.084	0.056	0.057	10.8	0.012	0.015	0.0017	0.075	0.0072	0.0053	0.0086	0.034	0.0089	11.2
SW2	0.012	0.063	0.058	0.037	0.046	27.0	0.013	0.038	0.0025	0.0601	0.0077	0.0047	0.0069	0.032	0.0086	27.4
SW3	0.032	0.066	0.099	0.066	0.084	16.4	0.017	0.023	0.0068	0.063	0.0075	0.0055	0.013	0.030	0.034	16.9
DW1A	0.0086	0.068	0.070	0.045	0.058	13.5	0.012	0.019	0.0019	0.060	0.0076	0.0046	0.0067	0.029	0.0060	13.9
DW1B	0.010	0.069	0.072	0.046	0.060	113.0	0.013	0.018	0.0022	0.064	0.0076	0.0050	0.0090	0.028	0.0066	13.4
DW2A	0.024	0.063	0.14	0.094	0.17	11.2	0.015	0.016	0.0052	0.083	0.0074	0.0055	0.026	0.026	0.0062	11.8
DW2B	0.023	0.063	0.147	0.090	0.17	9.85	0.015	0.014	0.0050	0.087	0.0071	0.0053	0.026	0.028	0.0063	10.5
DW3A	0.0094	0.070	0.061	0.039	0.076	19.0	0.012	0.027	0.0020	0.059	0.0075	0.0040	0.011	0.025	0.0069	19.4
DW3B	0.010	0.070	0.062	0.040	0.078	20.7	0.012	0.029	0.0021	0.050	0.0075	0.0042	0.012	0.021	0.032	21.1

S.P .	Turbidity (NTU) .	pH .	EC (μS/cm) .	TDS (mg/L) .	TH (mg/L) .	(mg/L) .	(mg/L) .	(mg/L) .	Cl− (mg/L) .	(mg/L) .	Na+ (mg/L) .	K+ (mg/L) .	Ca2+ (mg/L) .	Mg2+ (mg/L) .	Mn (mg/L) .	GPI .
	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	OW .	.
DS1	0.014	0.070	0.064	0.041	0.056	4.43	0.013	0.0063	0.0029	0.10	0.0062	0.0042	0.00842	0.054	0.026	4.90
DS2	0.037	0.071	0.064	0.041	0.068	10.9	0.018	0.015	0.0080	0.090	0.0060	0.0040	0.010	0.049	0.030	11.4
DS3	0.015	0.070	0.058	0.037	0.047	5.83	0.014	0.0082	0.0033	0.076	0.0068	0.0054	0.0070	0.038	0.0068	6.22
SW1	0.0077	0.070	0.084	0.056	0.057	10.8	0.012	0.015	0.0017	0.075	0.0072	0.0053	0.0086	0.034	0.0089	11.2
SW2	0.012	0.063	0.058	0.037	0.046	27.0	0.013	0.038	0.0025	0.0601	0.0077	0.0047	0.0069	0.032	0.0086	27.4
SW3	0.032	0.066	0.099	0.066	0.084	16.4	0.017	0.023	0.0068	0.063	0.0075	0.0055	0.013	0.030	0.034	16.9
DW1A	0.0086	0.068	0.070	0.045	0.058	13.5	0.012	0.019	0.0019	0.060	0.0076	0.0046	0.0067	0.029	0.0060	13.9
DW1B	0.010	0.069	0.072	0.046	0.060	113.0	0.013	0.018	0.0022	0.064	0.0076	0.0050	0.0090	0.028	0.0066	13.4
DW2A	0.024	0.063	0.14	0.094	0.17	11.2	0.015	0.016	0.0052	0.083	0.0074	0.0055	0.026	0.026	0.0062	11.8
DW2B	0.023	0.063	0.147	0.090	0.17	9.85	0.015	0.014	0.0050	0.087	0.0071	0.0053	0.026	0.028	0.0063	10.5
DW3A	0.0094	0.070	0.061	0.039	0.076	19.0	0.012	0.027	0.0020	0.059	0.0075	0.0040	0.011	0.025	0.0069	19.4
DW3B	0.010	0.070	0.062	0.040	0.078	20.7	0.012	0.029	0.0021	0.050	0.0075	0.0042	0.012	0.021	0.032	21.1

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To estimate the risk to humans due to heavy metal intake via drinking water, the CDI, the non-carcinogenic health risk of the detected heavy metals (Mn, Cd, and Cu), HQ, and the CR of As were compiled (Table 8). As shown in Table 8, the calculated HQ and CR values for both children and adult population groups were found to be less than 1, indicating that there was no carcinogenic and non-CR of the mentioned heavy metals due to ingestion of water from all sampling sites. However, the analysis of CDI and HQ values showed that the trace/heavy metal ingestion rate of children was higher than that of adults, which may pose health risk issues in the study area. Similarly, Belew et al. (2024) found that the CDI of Fe, Cu, Zn, Cd, Pb, Cr, and Ni in children was higher than that of adults. This suggests that children could be more vulnerable to non-cancer risks due to the ingestion of heavy metals (Munene et al. 2023). This could be due to children's lower body weight, differences in physiological factors, higher contact frequency, and distinct dietary habits (Khalid et al. 2020). Mn was found as the highest consumed element through ingestion (0.004–0.019 mg/L/day for children and 0.0011–0.0058 mg/L/day for adults) at all sites. Based on the HQ values, Cd ranked first for both children and adults at the sampling sites where it was detected. This revealed that it may induce a non-carcinogenic health risk as its measured concentration was also found above the threshold limit recommended by the WHO, particularly at DS1, DW_2A, and DW_3B. The ‘no risk’ category shown in Table 8 for all trace/heavy metals is based on the HQ value, which was less than 1 for all metals at all sampling sites. The CDI and HQ values of this study were found to be less than the values reported in the earlier studies for both population groups. Belew et al. (2024) reported a maximum HQ value of 95.34 (Cd) for children via ingestion and a minimum HQ of 2.05 × 10⁻⁶ (Ni) for adults. They stated that HQ values for children were higher than those of adults for all metals they analyzed. Emmanuel et al. (2022) reported high HQ indices (>1) for Pb, Hg, and Cd in drinking water. Another study found that the mean HQ values for Cd were 26.2 for adults and 12.8 for children, for Ni were 1.4 for adults and 0.7 for children, and for Pb were 244.4 for adults and 119.6 for children, all of which exceeded the expected values for drinking water samples (Nyambura et al. 2020). Rashid et al. (2019a,b) reported CDI of 0.01–0.013 and 0.008–0.011 mg/L/day Mn and 0.003–0.004 and 0.003 mg/L/day Cd for children and adults, respectively, and HQ of 0.07–0.09 and 0.06–0.08 Mn, and 6.29–8.13 and 5.39–6.97 Cd for children and adults, respectively, for the ground drinking water in Pakistan. Rashid et al. (2021) found that the HQ values of Ni, Cd, Pb, and Cu for both children and adults in the groundwater of Mardan, Pakistan, were greater than 1. Khattak et al. (2021) also reported that the pollution load index values of mercury in most of the groundwater samples in the district of Swabi, Pakistan, fell above the recommended value of 1, and hence, people who use these water sources for their domestic purposes could face health risks. Singh et al. (2022) found that 49% of the school children in Haryana, India, suffered from dental fluorosis due to the ingestion of underground water unfit for drinking.

The summarized comparison of the water quality parameters obtained in the present study, including the means of the parametric values derived from each type of drinking water source (DS, SW, and DW), with the national and international recommended levels of each parameter is presented in Table 9.

Table 9

Comparison of water quality parameters of the present study with the national and international quality standards of drinking water

Parameter .	This study means of sampling sites .			National and international quality standards of drinking water .
	DS .	SW .	DW .	ECS .	WHO .	BIS .	Canada .	FAO .	USPHS .
Turbidity (NTU)	1.95 ± 0.05	1.50 ± 0.02	1.26 ± 0.04	5	5	–	–	–	5
pH	6.96 ± 0.01	6.60 ± 0.00	6.67 ± 0.01	6.5–8.5	6.5–8.5	6.5–8.5	6.5–8.5	6.5–8.4	6.0–8.5
EC (μS/cm)	409.77 ± 2.81	531.22 ± 4.24	598.33 ± 3.91	1,000	300	750	–	750	300
TDS (mg/L)	262.25 ± 1.80	352.09 ± 2.82	390.60 ± 4.86	500	1,000	500	–	450	500
TA (mg/L)	224.88 ± 2.17	222.55 ± 2.23	233.99 ± 1.62	200	200	200	200	30–100	200
TH (mg/L)	226.33 ± 2.00	246.77 ± 1.73	409.33 ± 1.73	300	300	300	–	100–150	250
(mg/L)	3.74 ± 0.11	9.57 ± 0.08	7.70 ± 0.06	0.03	0.03	–	0.03	3	0.03
mg/L)	39.21 ± 0.33	36.63 ± 0.09	35.23 ± 0.14	250	250	200	–	50	–
(mg/L)	5.27 ± 0.17	13.57 ± 0.12	10.89 ± 0.12	50	50	45	50	45	50
Cl− (mg/L)	12.63 ± 0.36	9.72 ± 0.32	8.14 ± 0.16	250	250	250	–	–	–
(mg/L)	315.20 ± 38.87	233.11 ± 22.90	237.02 ± 47.00	–	200	300	–	–	–
Na+ (mg/L)	16.87 ± 0.84	19.74 ± 0.58	19.76 ± 0.45	200	200	200	–	–	–
K+ (mg/L)	2.41 ± 0.32	2.74 ± 0.17	2.52 ± 0.29	–	10	10	–	–	–
Ca2+ (mg/L)	17.00 ± 0.15	18.54 ± 0.12	30.08 ± 0.13	75	75	75	75	–	75
Mg2+ (mg/L)	62.32 ± 1.11	42.89 ± 0.29	34.76 ± 0.36	50	50	30	–	50	–
Mn (mg/L)	0.14 ± 0.00	0.11 ± 0.00	0.07 ± 0.00	0.5	0.5	0.1	0.05	–	–
As (mg/L)	0.08 ± 0.00	0.07 ± 0.00	0.08 ± 0.00	0.01	0.01	0.05	0.01	–	–
Cd (mg/L)	0.01 ± 0.00	0.01 ± 0.00	0.01 ± 0.00	0.003	0.003	0.01	0.005	–	–
Pb (mg/L)	ND	ND	0.01 ± 0.00	0.01	0.01	–	–	–	–
Cu (mg/L)	0.01 ± 0.00	0.02 ± 0.00	ND	2	2	0.05	1	–	2
TC (cfu/100 mL)	44.2 ± 1.1	45.3 ± 1.3	1,139.16 ± 7.90	0	0	0	–	-	0
FC (cfu/100 mL)	34.1 ± 0.7	27.4 ± 1.2	130.27 ± 2.96	0	0	0	0	–	0

Parameter .	This study means of sampling sites .			National and international quality standards of drinking water .
	DS .	SW .	DW .	ECS .	WHO .	BIS .	Canada .	FAO .	USPHS .
Turbidity (NTU)	1.95 ± 0.05	1.50 ± 0.02	1.26 ± 0.04	5	5	–	–	–	5
pH	6.96 ± 0.01	6.60 ± 0.00	6.67 ± 0.01	6.5–8.5	6.5–8.5	6.5–8.5	6.5–8.5	6.5–8.4	6.0–8.5
EC (μS/cm)	409.77 ± 2.81	531.22 ± 4.24	598.33 ± 3.91	1,000	300	750	–	750	300
TDS (mg/L)	262.25 ± 1.80	352.09 ± 2.82	390.60 ± 4.86	500	1,000	500	–	450	500
TA (mg/L)	224.88 ± 2.17	222.55 ± 2.23	233.99 ± 1.62	200	200	200	200	30–100	200
TH (mg/L)	226.33 ± 2.00	246.77 ± 1.73	409.33 ± 1.73	300	300	300	–	100–150	250
(mg/L)	3.74 ± 0.11	9.57 ± 0.08	7.70 ± 0.06	0.03	0.03	–	0.03	3	0.03
mg/L)	39.21 ± 0.33	36.63 ± 0.09	35.23 ± 0.14	250	250	200	–	50	–
(mg/L)	5.27 ± 0.17	13.57 ± 0.12	10.89 ± 0.12	50	50	45	50	45	50
Cl− (mg/L)	12.63 ± 0.36	9.72 ± 0.32	8.14 ± 0.16	250	250	250	–	–	–
(mg/L)	315.20 ± 38.87	233.11 ± 22.90	237.02 ± 47.00	–	200	300	–	–	–
Na+ (mg/L)	16.87 ± 0.84	19.74 ± 0.58	19.76 ± 0.45	200	200	200	–	–	–
K+ (mg/L)	2.41 ± 0.32	2.74 ± 0.17	2.52 ± 0.29	–	10	10	–	–	–
Ca2+ (mg/L)	17.00 ± 0.15	18.54 ± 0.12	30.08 ± 0.13	75	75	75	75	–	75
Mg2+ (mg/L)	62.32 ± 1.11	42.89 ± 0.29	34.76 ± 0.36	50	50	30	–	50	–
Mn (mg/L)	0.14 ± 0.00	0.11 ± 0.00	0.07 ± 0.00	0.5	0.5	0.1	0.05	–	–
As (mg/L)	0.08 ± 0.00	0.07 ± 0.00	0.08 ± 0.00	0.01	0.01	0.05	0.01	–	–
Cd (mg/L)	0.01 ± 0.00	0.01 ± 0.00	0.01 ± 0.00	0.003	0.003	0.01	0.005	–	–
Pb (mg/L)	ND	ND	0.01 ± 0.00	0.01	0.01	–	–	–	–
Cu (mg/L)	0.01 ± 0.00	0.02 ± 0.00	ND	2	2	0.05	1	–	2
TC (cfu/100 mL)	44.2 ± 1.1	45.3 ± 1.3	1,139.16 ± 7.90	0	0	0	–	-	0
FC (cfu/100 mL)	34.1 ± 0.7	27.4 ± 1.2	130.27 ± 2.96	0	0	0	0	–	0

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The turbidity of all the tested water samples surpassed the high desirable limit, 0 NTU, set by the ECS and the WHO, and the water samples at DS₂, SW₃, DW_2A, and DW_2B did not fulfill the clean water turbidity limit (0–2 NTU). The TDS level in the water samples at DW_2A and DW_2B exceeded the suitable TDS standard of drinking water, 500 mg/L. The TA, TH, ⁠, and EC levels exceeded the threshold limits set by ECSs and WHO drinking water quality guidelines. The Mg²⁺ level in the water samples at DS₁ and DS₂ exceeded the recommended limit (50 mg/L). The concentration of As at DS₁, DW_2B, DW_3A, and DW_3B, and Cd at DS₁, DW_1A, DW_2A, and DW_3B surpassed the acceptable limits defined by WHO. The TC and FC of 100% of the tested water samples exceeded the 0 cfu/100 mL permissible limit of ECSs and WHO drinking water quality guidelines, indicating significant fecal pollution of the drinking water sources. 100% of the studied water samples fell under very highly polluted water (GPI >2.5). The significant pollution of the water samples in the study area was contributed mainly by where the overall water quality (OW) values of all water samples were above 0.1. Based on the health risk assessment, Mn was the highest consumed element for both children and adults. The HQ values for both children and adults were less than 1, with children showing higher values, indicating that children could be more vulnerable to non-cancer risks due to the ingestion of heavy metals.

Generally, the water sources of the study sites were not deemed suitable for drinking as most of the water quality parameters did not meet the drinking water quality standards set by the ECS, BIS, WHO, USPHS, and FAO. There should be immediate treatment of the contaminated water using methods such as chlorination, UV treatment, or filtration to save people from waterborne diseases and avoid environmental risks.

The following measures should be taken to address the identified challenges and provide safe and clean drinking water.

(1) Implementing advanced water treatment technologies, such as activated carbon filtration, and reverse osmosis can effectively reduce contaminants concentration. (2) Watershed management practices, such as afforestation, erosion control, and sustainable agricultural practices, can help prevent the introduction of contaminants into water bodies. (3) The high levels of TC and FC in the studied water samples indicate significant exposure to human and animal fecal pollutants. Therefore, the local population should be well-informed, and government water administrators, kebele health extension workers, and concerned sectors should play crucial roles in taking protective measures, water quality monitoring, treating, and creating awareness to reduce pollution loads. (4) Regulatory measures and policy interventions should play a pivotal role in ensuring the long-term sustainability of drinking water quality. The study area water administrators and concerned sectors should establish an effective legal framework and implement it strictly to regulate and mitigate the pollution load on the drinking water sources. (5) Further research should be conducted incorporating more sites and seasonal variations of the year since the current research was limited to only one season (dry season) and three sites. Additionally, the Pb DL of the ICP-OES (0.042 mg/L) was above the maximum allowable concentration of Pb (0.01 mg/L). Thus, future studies should consider this limitation and use instruments with lower DLs.

There is no special fund or grant available for this research.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.