Bacteriological and physicochemical quality of drinking water and associated risk factors in Ethiopia

Abstract

The problem of drinking water quality is critical public health concern in Ethiopia in which poor sanitation and the use of contaminated water are blamed for 80% of disease cases. This is very important for monitoring water supply to identify and address any potential contaminants as well as investment in infrastructures and treatment technology that can improve water quality. This review aimed to evaluate the quality of drinking water in Ethiopia based on the concentration status of physicochemical and bacteriological parameters and its risk factors. Different studies in most parts of Ethiopia indicated that physicochemical quality of drinking water meet the prescribed standard limit, but in some parts of Ethiopia, water did not meet quality standard. Accordingly, an overall coliform count of drinking water in different areas of Ethiopia indicated that drinking water was at risk. Microbiological implications in the country showed that considerable amounts of drinking water were tainted with E. coli and fecal coliforms, which indicated the existence of dangerous pathogens. The quality issues several parts of Ethiopia were significantly influenced by poor handling practices. Consequently, proper handling practices of drinking water both at the source and point of use is essential to have a safe water supply and thereby protect public health. In order to guarantee that people have access to safe and clean water. The review’s findings underscore the urgent need for enhanced water quality monitoring and treatment in Ethiopia.

Keywords:

• Bacteriology
• Poor handling
• physicochemical quality
• Water

Public Interest Statement

Access to clean drinking water is fundamental human right and essential for maintaining public health and economic activity. It is better to ensure that people have access to clean drinking water. It is in the public interest to ensure a high quality and meets appropriate safety standards. Monitoring quality of drinking water is critical to prevent the spread of different diseases like skin disease, kidney damage, circulatory system problems, gastrointestinal stress, risk of cancer, blue baby syndrome, nervous system disorders etc. Microbial contamination is most common and widespread health risk associated with drinking water. The acute watery diarrhea is becoming one of the public health problems in developing countries especially in sub-Saharan countries. According to the World Bank report, only 42% of the population in the Ethiopia has access to improved water sources and water quality is often poor due to various potential contaminants like chemicals, microorganisms, industrial wastes, and toxic substances. Many children die annually due to diarrheal diseases. Thus, it is important to promote public awareness about drinking water quality to ensure that individuals and communities are informed about potential risk and how to protect themselves. Ultimately, ensuring access to safe and clean drinking water is shared responsibility that requires collaboration between government agencies, water suppliers, and consuming communities.

1. Introduction

Water quality and the risk of waterborne diseases are critical public health concerns in many developing countries like Ethiopia (WHO, 2017b). The term water quality describes the condition of the water by its chemical, physical, and biological characteristics. There are different parameters that describe these characteristics. These parameters have their own standard limits set by both WHO and national government according to their local condition. Therefore, water to be safe and acceptable for drinking purposes, it should have to fulfill the permissible standard limits (WHO, 2011). Safe drinking water means a water that does not represent any significant risk to health over a lifetime of consumption (WHO, 2008). Improper handling practice is one of the main causes for drinking water quality deterioration even though natural causes are expected (Adane et al., 2017; WHO, 2011). About 3.6 billion people lack clean drinking water, safely managed sanitation facilities, and various people practice open field defecation at global level (UNESCO, 2019). Improving the quality of water supply can reduce an incidence of different diseases (Ince & Smith, 2008).

Unhygienic water storage and handling practices are strongly associated with microbial contamination of drinking water (Shaheed et al., 2014). Microbial contamination is most common and widespread health risk associated with drinking water (Duressa et al., 2019). Deterioration of physical water quality does not affect health directly, but its presence can indicate risk of microbiological and chemical contamination. For instance, high turbidity in water can lead to growth of disease-causing pathogens such as bacteria (WHO, 2011). On the other hand, chemical parameters like fluoride, arsenic, and other toxic elements leached from underground rock formations can cause different health complications (Pritchard et al., 2008).

An accumulation of some chemical contaminants in drinking water can cause a high health risk due to exposure to chemicals (WHO, 2017b). Drinking water containing large amounts of metals can cause health problems ranging from shortness of breath to various types of cancer. Monitoring and measurement of these elements in drinking water are therefore essential and important for human health and safety assessment (Kamani et al., 2018). The biological toxicity of critical trace elements found in drinking water, like cadmium, chromium, arsenic, and lead, is significant and poses a threat to human health (Turdi & Yang, 2016). Heavy metal consumption over an extended period of time harms both people and other creatures. For instance, when levels of Cr, Cu, and Zn surpass their recommended threshold values in water, it can result in non-carcinogenic risks such brain involvement, headaches, and liver illness. Numerous human health issues could also result from both acute and chronic arsenic exposure. These included carcinogenic effects (such as liver cancer) and dermal, respiratory, cardiovascular, gastrointestinal, hematological, hepatic, renal, neurological, developmental, and reproductive impacts (Kamani et al., 2018)).

Globally, about 28 in 100 people lack access to sufficient and safe drinking water (WHO, 2017b). Several people in low- and middle-income countries exposed to sanitary risks. Sanitary risk scores of household vessels in low- and middle-income countries ranged from low to very high (Bain et al., 2018). Over 1.7 billion people live without gaining basic sanitation facilities and 709 million are in sub-Saharan African countries (WHO, 2019). Approximately, two-thirds of urban residents in low-income countries mainly in Africa are facing terrible water quality and sanitation problems (UNESCO, 2019). In sub-Saharan Africa, there was progress on sanitation facilities to achieve basic sanitation coverage (Ritchie & Roser, 2019; WHO, 2019). However, still only few countries achieved basic sanitation (WHO, 2019). Many people in Africa die every hour from diseases linked to poor sanitation, poor hygiene, and consumption of contaminated water (Ince & Smith, 2008).

Despite Ethiopia’s large water resource potential, the country suffers from low access to safe drinking water and adequate sanitation services (Demie et al., 2016; WHO, 2006). Safe drinking water access rate in Ethiopia is the lowest among sub-Saharan countries (Siraj & Rao, 2016). Due to frequent interruptions of piped water supply, drinking water in Ethiopia is commonly stored for a considerable lengths of time resulting in gross contamination (Adane et al., 2017; Chalchisa et al., 2018). Ethiopian demographic and health survey reported that people are exposed to different diseases due to water contamination and poor sanitation in different regions of Ethiopia, such as in Amhara, Gambelia, and southern region of Ethiopia (CSA, 2016). A study by Kassa (2017) in central Ethiopia showed that drinking water quality failed to conform with WHO quality standard. In addition, contamination of drinking water by Escherichia coli is common in Eastern Ethiopia (Asefa et al., 2021). As indicated by various findings in many parts of Ethiopia, drinking water from source to home contaminated chemically and bacteriologically. Consequently, drinking water in many area of Ethiopia failed to meet the prescribed standard limit of WHO (Asefa et al., 2021; Siraj & Rao, 2016; Usman et al., 2016).

Although water quality is influenced by natural factors, improper handling practices and poor sanitation were the main factors for drinking water quality degradation in Ethiopia (Asefa et al., 2021; Gebrehiwot et al., 2021; Mekonnen et al., 2019; Sitotaw & Nigus, 2021). Protecting drinking water quality is, therefore, a prime action to protect human health. Despite the prevalence of the water quality problem in Ethiopia, the concerned body did not give expected attention on this area. Therefore, the overall objective of this review paper was assessing bacteriological and physicochemical quality of drinking water and associated risk factors in different parts of Ethiopia.

2. Literature Review

2.1. Overview of Drinking Water Quality

Drinking water can be defined as water that is delivered to the consumers that can be used for drinking, cooking, and washing (Rajagopal, 2016). Drinking water quality describes the condition of water including the chemical, physical, and biological characteristics of water for a particular purpose (Boyd, 2015). Any physical, chemical, or biological property that influences the suitability of water for use by humans is a water quality variable. The term water quality refers to the suitability of water for a particular purpose (Boyd, 2015). Waterborne disease is one of the major health concerns in the world (Boyd, 2015). It is important to have improved water sources. Because, improving the quality of drinking water can result in a tangible benefit to human health (WHO, 2008). Sources of drinking water can be categorized as improved or unimproved sources. Improved sources include piped water into a dwelling, public tap or standpipe, tube-well or borehole, protected spring, protected dug well, and rainwater collection. Unimproved sources of drinking water include unprotected dug well; unprotected spring, cart with small tank or drum; tanker truck provided water and surface water (WHO, 2019).

2.2. Physicochemical Quality of Drinking Water

Physicochemical water quality and suitability for use are determined by its taste, odor, color, ionic concentration, pH, turbidity, electrical conductivity, total suspended solids, total dissolved solid, total organic carbon, hardness, nutrient contents, heavy metals and others Some physical parameters generally do not have health impacts. However, it can affect acceptability of consumers by affecting organoleptic properties of water (Boyd, 2015). Any parameter describing the status of drinking water has its own limit. In this regard, maximum contaminant limits of ionic concentrations and values of the physical parameter of water designed by different organizations are guides to use water for any purpose. Thus, any value beyond a maximum contaminant limits may cause problems (WHO, 2017a).

2.3. Bacteriological Quality of Drinking Water

Water used for human consumption should be free from microbial (WHO, 2017a). A lot of pathogens exist in water that can impair the microbiological quality of water. However, there are common microorganisms in water that can be used as a primary indicator of possible contamination and an index of water quality. The common microorganisms used as a primary microbial indicator are group of coliform bacteria, namely, total coliform, thermotolerant coliforms or alternatively Escherichia coli (E. coli) and Enterococcus (WHO, 2017a).

Total coliform bacteria consist of different types of bacteria that found in the environment such as in vegetation, in soil, and in human and animal feces. Total coliform can be harmful but some of it is harmless. Since its presence in the environment must not relate to fecal contamination especially in tropical countries, it is not recommended as indicator for fecal contamination in water. However, the presence of thermotolerant bacteria (fecal coliform bacteria), a sub-group of total coliform bacteria coming from human or animal feces is an indication of fecal contamination. It includes a group of genus Escherichia coli and some species of Klebsiella, Enterobacter, and Citrobacter (WHO, 2017a). It exists in sewage, in treated effluents, and in all-natural waters and soils subject to recent fecal contamination, whether from human, wild animals, or agricultural activity. According to all characteristics, Escherichia coli is the best indicator and gives conclusive evidence of fecal contamination in water (WHO, 2006). High total coliform counts in drinking water reveal high-risk scores that may indicate improper handling practices of drinking water and poor sanitary conditions (WHO, 2017a).

2.3.1. Drinking water quality in Africa

Globally, 2 billion people drink fecally contaminated water and 4.5 billion people use unimproved sanitation system. Over half of these people live in sub-Saharan Africa (WHO, 2018). Most of populations live in low-income countries. Africa suffers from health problems associated with contaminated water consumption (Abbas & Hassan, 2018). In many African countries people are facing a problem of inequalities in accessing improved water supply and sanitation (Armah et al., 2018). Provision of safe drinking water is a challenging issue in Africa. Population growth with increasing per capita consumption would require a significant increase in water supply (Armah et al., 2018). Around 70–80% of people in sub-Saharan Africa lack access to safe water and sanitation (Armah et al., 2018). A status of water, sanitation and hygiene service coverage in many African countries has declined in its quality (World Bank, 2017).

Many people in Africa die every hour due to diseases linked to consumption of contaminated water (UNDESA, 2005). Drinking water in Africa is highly affected by fecal contamination, which can be causes for different disease (Haileamlak, 2016). The acute watery diarrhea is becoming one of the public health problems in developing countries especially in sub-Saharan countries. This disease caused substantial morbidity and mortality (Haileamlak, 2016). As a surveys conducted by Lyons (2014) indicated that, 78% of total sub-Sahara African had poor performance of water quality. Nowadays, water sources are mainly polluted by agricultural practices and industrial chemical waste disposals due to cross contamination with sewerage, corrosions, and leakages (Wolde et al., 2020). An absence of hand-washing facilities also mainly affected bacteriological quality of drinking water in Africa. Generally, water contamination in Africa is mainly attached with improper water-handling practices (Singh et al., 2013).

2.3.2. Physicochemical quality of drinking water in Ethiopia

According to Ethiopian demographic and health survey, drinking water used by 14% of household with piped water in Ethiopia had moderate or high levels of residual chlorine (CSA, 2016). A study by Kassegne et al. (2020) in North Eastern escarpment of Ethiopian highland revealed that most of cations in water sources were below WHO and Ethiopian drinking water guidelines with exception of potassium, iron in most water sources and magnesium in semi-dry season. Nevertheless, some anions of spring water coincided with WHO standard limit, but no manganese was detected in water sources (Kassegne et al., 2020). Nationally, most of drinking water in Ethiopian did not have very high electrical conductivity, but 22% of water sources in Tigray region and 30% in other regions are characterized by high concentration of electrical conductivity (Kassegne et al., 2020). Similar finding in Gambella town of Western Ethiopia indicated that most of physicochemical parameters of sampled water were within permissible standard limits of WHO for drinking water. However, heavy metals were below detection limit except chromium and lead for some sampled water sources (Tesfaye et al., 2018).

A finding in Assella town in Ethiopia revealed that several tested physicochemical parameters in drinking water conformed to World Health Organization and Ethiopian drinking water standards of acceptable limits, except for residual chlorine (Gökçekuş et al., 2020). Another study in Gedeo Zone of southern Ethiopia indicated that most of tested physicochemical parameters of sampled drinking water never coincided with WHO standards (Aregu et al., 2021). This study was confirmed by findings by Werkneh et al. (2015) and Duressa et al. (2019) in other parts of Ethiopia. A similar study by Hailu (2017) in Addis Ababa of central Ethiopia showed that some of physicochemical parameters of sampled water sources were above WHO standards for drinking water in dry and wet seasons. However, pH, nitrate⁻, total alkalinity, total phosphorus, biological oxygen demand, sulfur, sulphate, copper, chloride, dissolved oxygen, and total suspended solid were below WHO standard limit for drinking water (Hailu, 2017).

An investigation by Fito et al. (2019) in Haramaya district of Eastern Ethiopia indicated that majority of physicochemical parameters were within permissible limits of Ethiopian standard and WHO standards for drinking water quality. However, few parameters like lead, cadmium, chromium, and total hardness from some sampled water sources failed to confirm with Ethiopian and WHO guideline for drinking water A related study by Abegaz et al. (2021) at Guto Gida district in Wolega zone of western Ethiopia revealed that, most of water sources showed marginally tolerable quality. In contrast to this, in terms of zinc, lead, iron, manganese, and pH of protected water sources were above WHO standard limit for drinking water (Abegaz et al., 2021). In addition, a finding by Kuma (2019) in Southwest Shoa zone of central Ethiopia also indicated that most of physicochemical parameters coincided with WHO standard for drinking water except temperature, pH, turbidity, and dissolved oxygen.

Drinking water sources in Sidama region of southern Ethiopia were found to be good for drinking in terms of their physicochemical quality (Meride & Ayenew, 2016). A similar study by Sitotaw and Nigus (2021) in northwestern Ethiopia showed that various physicochemical parameter of drinking water were within the permissible limit of WHO guidelines, except for turbidity and temperature. Relatively a similar study in Wolaita Zone of southern Ethiopia showed that a mean value of pH from sampled spring and tap water, total solids, total hardness, and total suspended solid from spring, tap, and well water were within acceptable range of Ethiopian standard as well as WHO standard. On another hand, fluoride, temperature, turbidity, electrical conductivity, total dissolved solid, and total alkalinity in sampled spring, tap, and well water were out of permissible standard limit of Ethiopian and WHO (Ashenafi and Alemu, 2022). Therefore, water sources need sustainable remedial action to make them safe for drinking (Ashenafi and Alemu, 2022). As indicated from Table 1, drinking water around central Ethiopia was suitable for drinking purpose with regard to pH, turbidity, total dissolved solids, electrical conductivity, free residual chlorine, phosphate, and nitrate concentrations (Duressa et al., 2019).

Table 1. Mean concentration of physicochemical parameters in drinking water in of Ethiopia

Parameter	Mean value	Remark	Standard limit (WHO, 2018)	References
Turbidity (NTU)	0.98	Acceptable	0.3–25 NTU	Meride and Ayenew (2016)
	1.36	Acceptable		(Gemeda et al., 2021)
	4.74	Acceptable		(Behailu et al., 2018)
Temperature(C)	28.49	Acceptable	15–35°C	(Meride & Ayenew, 2016)
	16.65	Acceptable		(Tewodros, 2019)
	22.22	Acceptable		(Behailu et al., 2018)
Total Dissolved Solid (mg/L)	118.19	Not acceptable	200–2500 mg/l	(Meride & Ayenew, 2016)
	805.07	Acceptable		(Behailu et al., 2018)
	282.125	Acceptable		(Tesfaye et al., 2018)
Electrical Conductivity (μS/cm)	192.14	Acceptable	170–2700 μs/cm	(Meride & Ayenew, 2016)
	0.97	Not acceptable		(Behailu et al., 2018)
	798.4	Acceptable		(Tesfaye et al., 2018)
Chloride (mg/L)	53.7	Acceptable	20–1200 mg/l	(Tewodros, 2019)
	32.90–85.77	Acceptable		(Fito et al., 2019)
	10.07–30.0	Not acceptable		(Faye et al., 2022)
Residual chlorine (mg/L)	0.05	Not acceptable	0.1–5.0 mg/l	(Gemeda et al., 2021)
	0.26	Acceptable		(Duressa et al., 2019)
pH	7.48	Acceptable	6.5–8.5	(Gemeda et al., 2021)
	7.61	Acceptable		(Tewodros, 2019)
	7.54	Acceptable		(Behailu et al., 2018)
Nitrate (mg/L)	2.53	Not acceptable	40–75 mg/l	(Tewodros, 2019)
	1.93–13.33	Not acceptable		(Fito et al., 2019)
	1.1–1.8	Not acceptable		(Faye et al., 2022)
Hardness (mg/L)	20.4	Not acceptable	100–1000 mg/l	(Tewodros, 2019)
	399.90	Acceptable		(Behailu et al., 2018)
	271.67–410.67	Acceptable		(Fito et al., 2019)

2.3.3. Bacteriological quality of drinking water in Ethiopia

People of Ethiopian in different parts of country consuming water were not safe for consumption. For instance, a community-based survey and cluster-randomized study in rural Ethiopia showed that stored drinking water at home was contaminated by fecal coliform (Usman et al., 2016). Various studies in several areas of Ethiopia showed that different sources of drinking water failed to comply with WHO’s criteria for drinking water quality standards (Asfaw et al., 2016; CSA, 2016; Duressa et al., 2019; Gizachew et al., 2020; Sitotaw & Nigus, 2021; Wolde et al., 2020). In Raya valley, groundwater was severely affected as a result of direct contact with brewery effluent (Estifanos et al., 2020). The authors found that several water quality parameters do not comply with WHO prescribed limit and thereby not safe for drinking. A related study by Asfaw et al. (2016) in Jigjiga city of eastern Ethiopia on 125 water samples showed that 20% of main source, 66.7% of local water suppliers, 80% of reservoirs, 30% of pipelines and 55% of home water were contaminated with E. coli. Another study by Ashuro et al. (2021) in Gedeo zone of southern Ethiopia showed that, 107 (50.2%) samples were positive for fecal coliforms from 213-sampled water. Water quality with regard to fecal and total coliform counts never conformed to WHO standards for drinking water and Ethiopian drinking water standards in Nekemte town of western Ethiopia (Duressa et al., 2019).

A finding by Sitotaw and Nigus (2021) in Kobo town of northern Ethiopia indicated that drinking water in the area was highly contaminated regarding its bacteriological quality. A presence of high coliform counts in drinking water in Kobo town was likely a threat to public health (Sitotaw & Nigus, 2021). A related study by Abegaz et al. (2021) conducted at Guto Gida district in Wollega Zone of western Ethiopia revealed that 90.6% and 87.5% of sampled drinking water were positive for total and fecal coliform, respectively. Consequently, this water is not recommended for drinking (Abegaz et al., 2021). A similar finding by Gökçekuş et al. (2020) at Assela town in Ethiopia revealed that only 75% and 62.5% of water samples were within the acceptable limits for fecal coliforms and total coliforms, respectively.

Another study by Alemayehu et al. (2020) in southern regional state of Ethiopia indicated that people were exposed to pathogen in half of improved water sources based on sanitary inspection risk score. Storing drinking water at home can lead to gross contamination of water. Household-stored drinking water was grossly contaminated with fecal coliform and fecal streptococci in the northern Ethiopian highlands. Household stored drinking in this area were characterized as significantly low and high-risk category due to fecal streptococci contamination of water (Feleke et al., 2018). Bacteriological quality of drinking water deteriorated from source to point of use in Harari region of eastern Ethiopia. Accordingly, high proportions of households’ sampled drinking water contaminated by thermotolerant coliform (Asefa et al., 2021). As study Sitotaw and Nigus (2021) in Wegeda town of northwestern Ethiopia showed that a median values of total and fecal coliform count ranged from 5 to 27 and 2 to 13 CFU/100 mL, respectively. Consequently, drinking water failed to confirm with WHO standards as well as Ethiopian standards for drinking purposes. Another study Hailu (2017) conducted in Addis Ababa from Legedadi reservoir of central part of Ethiopia on physicochemical and microbial quality of drinking water depicted that drinking water along distribution system was exposed to contamination and the quality of water declined along distribution system. High counts of coliforms detected in Legedadi from reservoir to household taps. Consumption of such water could bring an adverse effect on the beneficiary (Hailu, 2017).

A finding by Aregu et al. (2021) at Dila town of southern Ethiopia showed that drinking water was not safe to drink due to a presence of fecal coliform. High fecal and total coliform counts detected in sampled drinking water at Debre Tabor town of northern Ethiopia. This has resulted deterioration in bacteriological quality of water (Tasew, 2018). It is therefore vital to treat water prior to distribution for the beneficiary (Tasew, 2018). Another related study by Usman et al. (2016) in Fogera and Mecha district of northwest Ethiopia showed that from 61 sampled water sources, 58% of sampled drinking water from household and 73.77% from sources were contaminated by E. coli.

A similar study by Gebrewahd et al. (2020) in Tigray region of northern Ethiopia revealed that, around 34% of drinking water in this area had a high sanitary risk score. A study by Sitotaw and Nigus (2021) in Kobo town of northern Ethiopia showed that water in this area were not recommended to drink. The authors indicated that a significant proportion of drinking water was contaminated with Escherichia coli. A related study in Tigray region of northern Ethiopia also showed that Klebsiella species was a common pathogen in drinking water (Bekuretsion et al., 2018). Drinking water at Nekemte town of western Ethiopia was significantly contaminated by total coliform ranging from 12 to 120 CFU/100 mL, whereas fecal coliforms detected in only 37% of sampled tap water Duressa et al. (2019). Another study by Addisie (2022) in south Gondar zone of northern Ethiopia showed that drinking water contamination with coliform bacteria in the area was significant. Unimproved sources were generally unsafe to consume, even if utilized as an alternative water supply. (Addisie, 2022)

2.3.4. Hotspots of unimproved drinking water sources in Ethiopia

Damtew and Geremew (2020) showed hotspots of unimproved drinking water sources at national and regional levels in (Figure 1). Most of the clusters were in pastoral and rural areas of Afar, on the border of Amhara and Afar, Somalia, and Southern region of Ethiopia (Damtew & Geremew, 2020). Pastoralists are among the most poorly served population in Ethiopia, a country that has low levels of improved water access. This can be due to low priority for rural areas and pastoral communities (Damtew & Geremew, 2020). Moreover, water sources in these areas were few and far from a dwellers which could result in contamination of water between point of collection and consumption (Alemayehu et al., 2020; Whitley et al., 2019). Thus, these rural areas and pastoral communities were the most affected groups from diarrheal disease and related water-borne infections (Anthonj et al., 2018). In total, most households dependent on unimproved water sources were rural dwellers and a small number of households did not treat water prior to drinking. This could be related to low perception about the water quality associated health risks and the health benefits of treating drinking water (Damtew & Geremew, 2020).

Figure 1. Red colors indicate clusters with the highest percentage of unimproved water while, blue colors show clusters with low unimproved water coverage (Source: Damtew and Geremew (2020)).

2.4. Water Handling Practice in Ethiopia

On-site waste treatment and dumping of wastes in nearby water bodies is challenging issue in Ethiopia. A key challenge is that Ethiopia’s existing industries use old technologies and lacks facilities for on-site waste treatment. Roughly, 90% of existing industries dump their wastes in nearby water bodies particularly tanneries, brewery, textiles and coffee processing plants (UNDP, 2018). Majority of Ethiopians live in rural areas; but 43.5% of those residents use unprotected drinking water sources (UNDP, 2018). As indicated by Ethiopian demographic and health survey, a practice of water treatment in Ethiopia was very low, in which 88.4% of urban and 92.1% of rural household did not practice water treatment. Nearly 65% of households have access to an improved source of drinking water. However, only 6% of households in Ethiopia use improved sanitation. Approximately 9% of households use a shared facility, 53% use unimproved sanitary facility, and 32% have no sanitary facility (CSA, 2016).

A study by Asefa et al. (2021) in Harari region of eastern Ethiopia indicated that, drinking water treatment in the region was significantly poor. A finding by Chalchisa et al. (2018) indicated that sampled drinking water storage tanks in Jimma zone of southwestern Ethiopia were positive for coliform bacteria. This study also confirmed that leakage in a distribution system was obvious. Poor handling of storage tank in this area was also witnessed (Chalchisa et al., 2018). A findings by different scholars indicated that, narrow mouthed water storage containers were common in different parts of Ethiopia as revealed in the Figure 2 (Asfaw et al., 2016; Berhanu & Hailu, 2015; Gizachew et al., 2020). There was strong association between a water collection container and coliform contamination of drinking water. Narrow mouthed storage containers were difficult to clean properly after emptying (Usman et al., 2016). Households that use Jerrycan to collection or store water had 2.6 times higher Escherichia coli concentration than household using pot (Usman et al., 2016).

Figure 2. Status of drinking water sources and poorly managed (backflow, flooding, and broken pipe) water sources in South Gondar zone of northern Ethiopia (Source: Addisie (2022)).

At Kobo town of northern Ethiopia, a community practiced poor water handling practices. Most of consumers dump a waste around the water source and the reservoir (Sitotaw & Nigus, 2021). Another study by Yasin et al. (2015) in Jimma zone of southwest Ethiopia showed that 50% of a community rely on open field waste disposal. A similar study by Abate (2016) in Tembaro district of southern Ethiopia, indicated that 55% of a sampled population dispose waste on an open field. Another study by Desissa (2016) in north eastern Ethiopia showed that drinking water was exposed to animal wastes due to inadequate fencing around a water sources. A community-based survey in rural Ethiopia indicated some household used water treatment like chlorination but they were not using it regularly (Usman et al., 2016). Water quality at Bahir Dar city of northern Ethiopia significantly exposed to point and non-point source of pollutants (Alemu, 2022). A study by Berhanu and Hailu (2015) in Sidama region of southern Ethiopia revealed that, water sources were poorly protected; a management practices were unhygienic; no proper diversion ditch around water sources and there were communal bathing near a water sources. A similar study by Kassie and Hayelom (2017) at Farta district in northwest Ethiopia indicated that 37.5% of a sampled population used unprotected water sources indicating a water supply at sources were exposed to animal entry.

2.5. Risk Factors of Water Contamination in Ethiopia

Water can be contaminated with pathogens at sources, during distribution, transportation, or handling in households or other working places (LeChevallier, 2013). In most countries, principal risks to human health associated with consumption of polluted water are microbiological in nature (WHO, 1997). Good handling practices of drinking water are essential for decreasing health risk (Feleke et al., 2018). A study by Wagari et al. (2022) in Haramaya district of Eastern Ethiopia indicated that prevalence of childhood diarrhea was statistically associated with water quality and sanitation service. A risk of acquiring waterborne infection increases with concentration of coliform load in drinking water (WHO, 1997). Thus, improving water handling practices can improve drinking water quality and thereby reduce health risk related to water quality problems (WHO, 2017a).

As indicated by various findings, risk factors of water quality deterioration in Ethiopia mainly attached with poor water handling practice. Various researchers as elaborated below confirmed this. A study by Gebrewahd et al. (2020) in north eastern Ethiopia revealed that, 21.6%, 34.1% and 10.6% of associated risk factors for drinking water contamination were animal excreta around a source, inadequate fences, and presence of pond water around the concrete floor respectively (Figure 3). Similar study in Kobo town revealed that main risk factors for water quality deterioration include unhygienic water handling practices at the household level and unhygienic environmental conditions around water sources, reservoir, and distribution line (Sitotaw & Nigus, 2021). Water contamination in several rural Ethiopia is attributed to washing clothes around water sources and unmanaged animal entry (Kassegne et al., 2020).

Figure 3. Sanitation status of drinking water in Ethiopia’s Somali Region (Source: Niculescu, 2019).

A finding by Duressa et al. (2019) at Nekemte town of western Ethiopia showed that, prevalence of indicator bacteria in drinking water mainly associated with poor waste disposal systems and management of water sources. Another study by Wagari et al. (2022) in Haramaya district of Eastern Ethiopia revealed that poor water handling practices were main cause for water contamination. A similar study by Sitotaw et al. (2021) in Wegeda town of northwest Ethiopia indicated that, poor protection of drinking water sources, educational status, occupation, family income, access to quality toilets, and another drinking water handling practices were major causes of drinking water contamination. Another study by Abegaz et al. (2021) in Guto Gida district of western Ethiopia indicated that corrosion of materials used for construction and pollutant from agricultural area contaminated drinking water sources.

Poor water handling practices were principal causes for bacteriological water quality deterioration in water stressed areas in Harari region of eastern Ethiopia (Gebrehiwot et al., 2021). Another study in Gambella region of western Ethiopia indicated that educational level of caregivers; unimproved water sources, water supply interruptions, and lack of free residual chlorine were principal predictors of fecal coliform contaminations of stored water (Mekonnen et al., 2019). A related study by Berhanu and Hailu (2015) in Sidama region of southern Ethiopia revealed that inadequate protection of water sources and unhygienic management practices were main risk factors. Another study by Asfaw et al. (2016) indicated that a main exposure for fecal contamination were constructional defects, poor sanitation, low level of hygiene awareness and irregular disinfection of drinking water (Table 2). Another finding Alemu (2022) in Bahir Dar city of northern Ethiopia revealed that main factors for water contamination were seepage of wastewater to a shallow groundwater from improperly constructed sanitation facilities, animal dung from animal breeding area and seepage of fertilizers from agricultural area.

Table 2. Category of risk score of water contamination according to (WHO, 1997) in various parts of Ethiopia in terms of coliform count per 100 milliliter of sampled drinking water

CFU/100 mL of water	Studied area/location	Risk category	Remark	References
2–100	Wolaita zone of southern Ethiopia	Low to intermediate risk	Contaminated water	(Gizachew et al., 2020)
21–204	Addis Ababa city of central Ethiopia	Low to high risk	‘’	(Wolde et al., 2020)
2–6	Harari Region of Eastern Ethiopia	Low risk	‘’	(Asefa et al., 2021)
43–50	Gambella town in western Ethiopia	Intermediate risk	‘’	(Mekonnen et al., 2019)
9–266	Debre Tabor town in northern Ethiopia	Low to high risk	‘’	(Tasew, 2018)
10–100	South Gondar zone of northern Ethiopia	Intermediate risk	‘’	(Addisie, 2022)
10–65	Jigjiga city of Eastern Ethiopia	Intermediate risk	‘’	(Asfaw et al., 2016)
10–147	Ankober district of northern Ethiopia	Low to high risk	‘’	(Kassegne et al., 2020)
10–100	South east Ethiopia	Intermediate risk	‘’	(Mohammed, 2017)

Note: CFU/100 mL = coliform count per 100 milliliter of sampled water

3. Conclusion and Recommendations

3.1. Conclusion

Water is crucial matter to sustain life, and safe supply of drinking-water must be available to all human. However, drinking water contamination is critical issues in Ethiopia. So, conducting research is a key issue which can be an informative or point out the quality issues and then strengthens water quality monitoring and control systems. Thus, this review intended to evaluate bacteriological and physicochemical quality of drinking water and associated risk factors in Ethiopia. The review revealed that majority of physicochemical parameters of drinking water in various parts of Ethiopia coincided with world health organization (WHO) or Ethiopian standard limits. For instance, a study in central Ethiopia strengthened this statement. However, some physicochemical parameters of drinking water in different parts of Ethiopia never conformed to standard limits. Few parameters like an electrical conductivity, temperature, some of heavy metals, nitrate, chloride, hardness, and solids in some parts of southern Ethiopia failed to comply with prescribed standard limits. In some rural areas of Ethiopia, tap water and open hand dug well had characterized turbidity values above prescribed standard limit. Regarding to bacteriological quality, drinking water in various parts of Ethiopia (i.e. northern, southern, western and eastern) was highly contaminated and this indicates its inconformity with standard limit for drinking water quality. Indicator bacteria (coliform) were detected in drinking water in various parts of Ethiopia. A contamination level concerning coliform count was an indication of vulnerability of water to microbial contamination. As proven by different scholars in Ethiopia, risk factors for contamination of drinking water in Ethiopia were mainly linked to improper handling practices. Accordingly, absence of fencing around water sources allowing an entrance of animals, dumping wastes at open field, underground leakage of wastewater, open defecation, bathing near water sources were main factors affecting water quality. Most of rural communities in Ethiopia particularly those living in pastoral areas were highly vulnerable to water contamination. Therefore, an integrated action of government, any organization, and consuming community to tackle this quality issue is very crucial.

3.2. Recommendations

Based on the literature reviewed and the author’s personal familiarity in the area, the following recommendations forwarded to take action in order to control water quality deterioration:

• Therefore, all concerned bodies shall strengthen water quality monitoring and control systems as well as regular risk assessment.

• A concerned body should encompass an integrated management of government bodies, consuming community and nongovernment organization.

• Detailed and regular risk assessment is, needed from treatment to distribution system including storage and safe handling of water at the source and the point of use in order to provide complete intervention strategies in tackling waterborne diseases.

• Community-based sustainable awareness creation programs regarding to water resources management from sources to point of uses and sound water supply chain management systems are a cornerstone to protect water contamination.

• If further reviewer should take continuous surveillance of water quality on a regular basis, public awareness creation, and the adoption management give valuable figure over the study area.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data availabilities were applicable from the online sources.

Additional information

Funding

The authors did not receive any funds for this manuscript.

Notes on contributors

Abera Atumo Ante

Abera Atumo Ante is Lecturer and Researcher in school of Natural Resources Management and Environmental Science, Haramaya University, Ethiopia. He is specialized in Environmental Sciences and Management (MSc) from Haramaya University. His research interest is Water quality, waste management, watershed delineation, environmental sanitation, and environmental impact assessment.

Girma Asefa Bogale

Girma Asefa Bogale is Lecturer and Researcher in school of Natural Resources Management and Environmental Science, Haramaya University, Ethiopia. He is specialized in Agro Meteorology and Natural Risk Management (MSc) from Haramaya University. His research interest is DSSAT_crop_model, Markism_climate_model, GIS, AquaCrop, Rprogram_RClimdex, Stata software analysis on impacts of climate change and adaptation.

Biniyam Mohammed Adem

Biniyam Mohammed Adem is Lecturer and Researcher at Haramaya University, Ethiopia. He is specialized in Water and health (Water and wastewater treatment (MSc)) from Addis Ababa University, Ethiopia. His research interest is on Water quality assessment, water supply, sanitation and water resources management.