Socioeconomic predictors of access to improved water sources, sanitation facilities, and household water treatment in Nigeria

Safe water and sanitation are essential not only for health and well-being but also for their impact on everyday life. Water used for drinking, irrigation, bathing, and various household purposes can become contaminated, and consumption of contaminated or unsafe water results in poor health outcomes, such as diarrhea, neglected tropical diseases (NTDs), and even death (World Health Organization [WHO] 2022a). Therefore, having access to improved water sources and sanitation facilities is considered a right that is fundamental to enjoying other human rights (Armah et al. 2018; Kayser et al. 2019). According to WHO (2022b), an improved water source is one that is protected from outside contamination, especially from fecal matter, while an unimproved water source is not protected from outside contamination. An improved sanitation facility is one that hygienically separates excreta from human contact while an unimproved sanitation facility does not offer this protection (WHO 2022b).

Household water, sanitation, and hygiene (WASH) sources have been shown to have crucial socioeconomic development and health implications. In low-income or developing countries, most water-borne diseases have been associated with drinking unsafe water. In Africa, more than 2,000 people die every day from illnesses that are related to poor sanitation and hygiene, and drinking unsafe water (Abubakar 2019). Limited access to safe drinking water and improved sanitation facilities, as well as improper or lack of water treatment practices, can promote the spread of water-borne diseases (Omole & Ndambuki 2014; Prüss-Üstün et al. 2018).

Household water treatment (HWT) is an important public health intervention for improving drinking water quality and reducing the incidence of water-borne diseases (WHO 2023a). HWT is the process of removing or inactivating microbial pathogens at the point of collection or consumption to improve water safety (WHO 2009). HWT serves as an intervention for those who may use unimproved or contaminated water (WHO 2011). According to the WHO, chlorination, alum, filters, allowing water to settle, straining water through a clean cloth, boiling, and solar disinfection are suitable HWT methods (WHO 2011). Chlorination chemically disinfects water by removing pathogenic bacteria and viruses; however, it does not remove protozoa (WHO 2011; Flanagan et al. 2013; Mengistie et al. 2013). Using alum is an effective coagulant that destabilizes tiny particulate matter suspended in water, and sedimentation allows suspended particles in turbid water to settle and get separated from the water (Lantagne et al. 2006; Abubakar 2021, p. 2). The use of filters and straining water through cloth expels microorganisms through size exclusion, though this is a time-consuming process (Sobsey & WHO 2002; Kohlitz et al. 2013; Nair & Kani 2017). Boiling water is a common and effective method of killing most water-borne microorganisms (Brown & Sobsey 2012). Solar disinfection for at least 6 h is an affordable method that effectively inactivates water-borne pathogens; however, this is a very time-consuming process (Dessie et al. 2014). Using an ultraviolet lamp also eliminates germs; however cost, lack of electricity, and maintenance may make this a less feasible option. Boiling and chlorination kill organisms that cause diarrhea, and solar disinfection inactivates them, while filtering, alum, and straining water can only help remove them (Albert et al. 2010; Blanton et al. 2010; Simukonda et al. 2018). Unfortunately, 2.1 billion people around the world do not have access to improved water sources, 2.3 billion do not have improved sanitation facilities (Emenike et al. 2017; Kayser et al. 2019), and many do not have adequate means of treating water to make it safe for use.

Nigeria is one of the 46 sub-Saharan African countries that has been most impacted by the global WASH issue. According to the Federal Ministry of Water Resources (FMWR) 2011 report, 42% of the Nigerian population did not have access to safe water supply while 62% did not have access to sanitation. By 2015, roughly 67% of Nigeria's population had access to improved drinking water sources (which was about 10 percentage points away from its Millennium Development Goal (MDG) water target of 77%; Emenike et al. 2017). In addition, more than 40% of the Nigerian population uses water sources with a very high risk of contamination (Abubakar 2019; WHO & UNICEF 2021). In Nigeria, poor access to improved water and sanitation continues to be a dominant contributing factor to elevated morbidity and mortality rates among children under five (Ezeh et al. 2014; UNICEF 2018; Nwokoro et al. 2020; Arowosegbe et al. 2021). According to UNICEF (2018), the use of contaminated drinking water and poor sanitary conditions have led to increased susceptibility to water-borne diseases such as diarrhea which leads to the deaths of more than 70,000 children under five annually. Nwokoro et al. (2020) conducted a study in Enugu, southeast Nigeria, which found that the prevalence of diarrhea in the 2 weeks preceding the study was 7.47% among all ages and 10.77% among children under five. Currently, 29% of the Nigerian population is fulfilling SDG target 6.1.1 of using safely managed drinking water, and 44% is fulfilling SDG 6.5.1 water management target (United Nations 2023a, 2023b).

Socioeconomic factors, such as poverty level, education level, and residence type (urban or rural), have important implications for access to safe water and sanitation and health behavior (Adams et al. 2016; Emenike et al. 2017; Abubakar 2019; Rodriguez 2019). In a secondary data analysis of the 2008 Ghanaian Demographic and Health Surveys (GDHS), Adams et al. (2016) found that poverty level, education level, and region/type of residence were among significant predictors of access to an improved drinking water source. In another study conducted by Irianti et al. (2016) using 2007 Indonesian family life survey data, the researchers found education, wealth, toilet type, and place of residence to be among significant determinants of household drinking water sources in Indonesia.

A study conducted by Akoteyon (2019) focused on rural settlements in parts of southwest Nigeria found that the majority of the households – of which most were low-income – relied on unimproved water sources and sanitation facilities. Emenike et al. (2017)’s study on southwest Nigeria found that increased income was correlated with access to improved water sources. Similarly, Rotowa et al. (2015) in Akure, a city in southwestern Nigeria, found that Nigerians who earned higher income used improved sanitation facilities and that Nigerians in Akure whose education level was below tertiary education used unimproved sanitation facilities. That study also found that the least proportion of Nigerians who used unimproved sanitation facilities had a tertiary level of education and that the use of unimproved sanitation facilities decreased as the level of education increased.

Despite the poor state of WASH-related affairs in the country, it is important to highlight efforts that country leadership is taking to rectify WASH-related issues in Nigeria. When President Muhammadu Buhari declared the State of Emergency in 2018, the Nigerian government also launched a National Action Plan (NAP). The NAP is a 13-year strategy for the Revitalization of Nigeria's WASH sector ‘aimed at ensuring universal access to sustainable and safely managed WASH services by 2030, commensurate with the SDGs’ (World Bank 2021, p. 5). In addition to that, the government has also created initiatives to address the factors that have restricted Nigerians from accessing safe and portable water. This effort is supported by the World Bank and other development partners (World Bank 2021).

One of these initiatives is the National Urban Water Sector Reform Program (NUWSRP), which includes objectives pertaining to ‘sector reform, water utility sustainability and commercial viability, infrastructure improvement, service reliability and performance enhancement, and increased access to quality piped water networks in urban areas nationwide’ (World Bank 2021, p. 7). According to the World Bank (2021), program achievements include the construction of more than 2,300 additional water points, and 6,546 sanitation compartments and hygiene facilities across Nigeria; the creation of 12,435 direct and 24,870 indirect jobs since 2015; and the certification of 33 Local Government Areas (LGAs) within 9 States as Open Defecation Free (ODF).

Another effort is the Nigeria Sustainable Urban and Rural Water Supply, Sanitation and Hygiene (SURWASH) Program, also supported by the World Bank, which is designed to enact essential policy reforms and strengthen the capacity of important institutions for sustainable and effective service delivery (World Bank 2021). This facilitates investments that increase access to and use of WASH services in urban and rural areas, as well as small towns. This includes the development of priority infrastructure to improve water supply service delivery and WASH infrastructure in institutions (schools and healthcare facilities) and public places such as markets and motor parks. The SURWASH Program is expected to provide 6 million Nigerians with basic drinking water services, support 1.4 million Nigerians in accessing improved sanitation services, advance improved WASH services in 2,000 schools and health care facilities, and aid 500 communities in achieving ODF status (World Bank 2021).

In studies similar to this current one that were conducted on other developing countries, poverty level has been strongly associated with the use of unimproved WASH sources as wealthier households have been found to have more access to clean water and improved sanitation facilities, and are thus more likely to use improved sources (Arouna & Dabbert 2010; Adams et al. 2016; Irianti et al. 2016; Mulenga et al. 2017; Abubakar 2019). According to Armah et al. (2018), lower level of education has been determined to specifically have ‘direct influence on affordability and decision-making capacity of households regarding access to water and sanitation services’ (p. 9). Additionally, households in rural areas and urban slums have less access to improved water and sanitation facilities compared to urban households (Armah et al. 2018). Overall, socioeconomic factors, such as education level, poverty level, and residence type, can influence the type of resources that people have access to. The review of the literature revealed a dearth of research on the relationships between socioeconomic factors and WASH in Nigeria and that the relevant studies on Nigeria are focused on southwestern Nigeria. This current study has not been conducted on Nigeria holistically. Therefore the objective of this study was to investigate the socioeconomic factors associated with access to improved drinking water sources and sanitation facilities, and HWT in Nigeria.

We used cross-sectional data from the 2018 Nigeria Demographic and Health Surveys (NDHS) for this study. This was the latest NDHS at the time of this study. Data collection occurred from 14 August to 29 December 2018. The Population and Housing Census of the Federal Republic of Nigeria (NPHC) was the sampling frame used for the 2018 NDHS. The sampling frame for the DHS is a list of enumeration areas (EAs) from a recent population census. Prior to sample selection, all neighborhoods were classified into urban and rural areas, based on predetermined minimum sizes of urban areas (any neighborhood exceeding a minimum population size of 20,000 was classified as urban; NPC & ICF 2019). The 2018 NDHS included people aged 15–49 in the sample households; 40,427 households were successfully interviewed, yielding a response rate of 99% (NPC & ICF 2019).

The independent variables in this study were residence type (urban or rural), highest level of education attained (No education/preschool, Primary, Secondary, Higher, and Don't know), and poverty level (Poorest, Poorer, Middle, Richer, Richest). All of the independent variables were categorical. In the NDHS, wealth/poverty level is a measure of household economic status using ownership of ‘assets: bank account, vehicle, air conditioner, television, radio, computer, cell phone, farmland and livestock’ (Abubakar 2019). The wealth quintiles were constructed from the raw data files after the data had been collected. Each household asset for which information was collected was assigned a weight or factor score which was determined through principal components analysis. The resulting asset scores were standardized relative to a standard normal distribution with a mean of 0 and a standard deviation of 1. These standardized scores were then used to establish the break points that define wealth quintiles (DHS, n.d.-b).

The dependent variables in this study were source of drinking water, type of sanitation facility, and HWT. All of the dependent variables were categorical. Based on WHO and UNICEF's categorization, the source of drinking water, and type of sanitation facility variables (Croft et al. 2018) were recoded into two categories: improved sources (1) and unimproved sources (0). Improved water sources included piped water into dwelling, yard or plot, public tap or standpipe, tube-well or borehole, protected dug well, protected spring, and rainwater. Unimproved water sources included unprotected dug well, unprotected spring, and surface water sources (i.e., rivers, ponds, and streams). Improved sanitation facilities included flush toilet, septic tanks, pit latrine with slab, ventilated improved pit (VIP), and compost toilet. Unimproved sanitation facilities included pit latrines without slab, bucket latrines, publicly shared latrines, and open defecation in bush or field (Croft et al. 2018; NPC & ICF 2019).

Descriptive statistics was used to describe the variables in the study. Binary logistic regression was conducted on the entire study population, after which two sub-group analyses were conducted based on household responses, to understand the impact of the predictor variables on HWT among Nigerians who reported not having access to improved water sources. The first sub-group analysis was conducted on those who reported not having access to improved water sources, and the second sub-group analysis included those who reported not having access to improved water sources and also not having access to improved sanitation facilities. Missing data were identified through descriptive statistics. DHS Survey documentation and consultation indicated that missing data are missing at random (MAR; DHS n.d.-a) In order to properly identify data that were not MAR, I used the exclude cases pairwise option in SPSS. This option excluded the case only if it was missing the data required for analysis. The case was still included in any of the analyses for which it had complete data for the independent and dependent variables. In total, five logistic regression models were conducted to investigate the socioeconomic factors associated with HWT and access to improved drinking water sources and sanitation facilities in Nigeria. All data analyses were performed in IBM^® SPSS Statistics for Windows, version 28.

For this study examining the socioeconomic factors associated with access to improved drinking water sources and sanitation facilities, and HWT in Nigeria, we used logistic regression analyses to determine how residence type, education level, and poverty-level affect access to improved water sources and sanitation facilities, and HWT in Nigeria. We also used descriptive statistics to determine the proportion of Nigerians who treated their drinking water to ensure that it was safe, and of those that did – what approach they implemented to do so. Table 1 provides a descriptive breakdown of the study variables and Table 2 displays the proportion of Nigerians that implemented specific types of measures to ensure that their drinking water was safe. The majority of surveyed Nigerians lived in rural areas (56%), used an improved source for drinking water (73%), used an improved sanitation facility (55%), and did not treat their drinking water (92%).

Table 3 displays the results of the logistic regression and shows that Nigerians who lived in a rural area were significantly less likely to have access to an improved water source. The results also showed that those who had a primary level, secondary level, or higher level education, were significantly more likely to have access to an improved water source compared to those with no education/preschool-level education. Likewise, Nigerians in the poorer, middle, richer, and richest wealth quintiles were significantly more likely to have access to an improved water source compared to those in the poorest wealth quintile.

With regard to access to improved sanitation facilities, the results indicate that Nigerians who lived in a rural area were significantly less likely to have access to an improved sanitation facility. The results also showed that those who had a primary level and secondary level education were significantly less likely to have access to an improved sanitation facility compared to those with no education/preschool-level education. Nigerians with higher level education were significantly more likely to have access to an improved sanitation facility compared to those with no education/preschool-level education. Additionally, Nigerians in the poorer, middle, richer, and richest wealth quintiles were significantly more likely to have access to an improved sanitation facility compared to those in the poorest wealth quintile (Table 3).

With regard to HWT, the results in Table 3 showed that among the entire study population, Nigerians who lived in a rural area were significantly less likely to treat their drinking water. The results also showed that those who had a primary level, secondary level, and higher level education were significantly more likely to treat their drinking water compared to those with no education/preschool-level education. Also, Nigerians in the richest wealth quintile were significantly more likely to treat their drinking water compared to those in the poorest wealth quintile. Nigerians in the middle, and richer wealth quintiles had the same likelihood as the poorest to treat their drinking water, while Nigerians in the poorer wealth quintile were less likely than the poorest Nigerians to treat their drinking water (Table 3).

Since having access to improved water might influence the decision to treat drinking water, sub-group analyses were conducted. These sub-group analyses revealed that Nigerians without access to improved drinking water sources who lived in a rural area were significantly less likely to treat their drinking water. The results also showed that for this sub-group, those who had at least a primary level of education were significantly more likely to treat their drinking water compared to those with no education/preschool-level education. Additionally, Nigerians in the poorer and higher wealth quintiles were significantly more likely to treat their drinking water compared to those in the poorest wealth quintile (Table 4). As far as Nigerians living in rural areas who did not have access to improved drinking water sources and improved sanitation facilities, sub-group analyses revealed that those who had a primary or secondary level of education were significantly more likely to treat their drinking water compared to those with no education/preschool-level education. Finally, Nigerians in the middle and higher wealth quintiles were significantly more likely to treat their drinking water compared to those in the poorest wealth quintile (Table 4).

In this study, we analyzed the socioeconomic factors associated with access to improved WASH and HWT in Nigeria. The results of this study confirmed the hypothesis that Nigerians living in rural areas who had lower levels of education, or were poorer, had less access to improved water and sanitation sources, and were less likely to treat their water. Analyses conducted on the entire study population showed that Nigerians living in an urban area were 2.38 times more likely to have access to an improved water source, and 1.27 times more likely to have access to an improved sanitation facility. Nigerians who had at least a primary level of education were about 1.20 times more likely than those with no education to have access to an improved water source, while Nigerians who had the highest level of education were 1.13 times more likely to have access to improved sanitation than those who had no education (Table 3).

Nigerians with a primary and secondary level of education were 1.19 and 1.20 times less likely to have access to improved sanitation compared to those with no education, respectively – an unusual finding that came as a surprise. The richest Nigerians were 67 times more likely to have access to an improved water sources and 171 times more likely to have access to an improved sanitation facility compared to the poorest Nigerians.

With regard to HWT, for the entire study population, Nigerians living in an urban area were 1.11 times more likely to treat their water compared to Nigerians living in a rural area. Those who had at least a primary level of education were at least 1.14 times more likely to make their water safe for use. The richest Nigerians were also twice as likely to take measures to treat their water compared to the poorest Nigerians. The results of the sub-group analyses were consistent with those seen in the entire study population. Sub-group analyses revealed that Nigerians living in an urban area were more likely to treat their water compared to Nigerians living in a rural area. Those who had at least a primary level of education were also more likely to treat their water, and the odds of HWT increased successively with an increased level of education. This pattern can also be seen for wealth level, in which the odds of HWT increased with increased wealth level.

Overall findings from this study are consistent with other studies in that that Nigerians living in rural areas, who have lower levels of education, and are poorer, are less likely to have access to improved water sources and sanitation facilities; and are less likely to treat their water (Arouna & Dabbert 2010; Rotowa et al. 2015; Adams et al. 2016; Irianti et al. 2016; Emenike et al. 2017; Mulenga et al. 2017; Armah et al. 2018; Abubakar 2019; Akoteyon 2019; Rodriguez 2019) and it comes as no surprise that Nigerians who have attained a higher level of education and wealth have the better outcomes. Education and poverty level, as well as geographical region, are socioeconomic factors that have a direct impact on the type of resources that people have access to and their ability to afford resources to achieve safe water. It is not surprising that those who have less education likely have lower paying occupations and are therefore poorer and live in less developed (i.e., rural) areas. In turn, they do not have the same access to developed infrastructure that makes way for improved water sources and sanitation facilities. This is not to say that people in rural areas or with less education are incapable of implementing HWT – rather, it is likely because they cannot afford to and do not have the necessary resources readily available.

Poor or limited access to improved WASH in Nigeria is a leading contributing factor to high morbidity and mortality rates among children under the age of five (UNICEF 2018). The use of contaminated drinking water and poor sanitary conditions make Nigerians more vulnerable to water-borne diseases including diarrhea – the cause of more than 70,000 cases of mortality among children under five each year (UNICEF 2018). Additionally, 73% of the diarrheal and enteric disease burden is linked with poor access to adequate WASH – a disparity faced by poorer children (UNICEF 2018).

According to the World Bank (2021), Nigeria's WASH sector was declared to be in a state of emergency by the government in 2018. In 2019, a combination of ‘inadequate infrastructure, a lack of required human capital, poor investment, and a deficient enabling regulatory environment – amongst other challenges – meant that approximately 60 million Nigerians were living without access to basic drinking water’ (World Bank 2021, p. 2). In addition to that, 80 million Nigerians did not have access to improved sanitation facilities, while 167 million could not access basic handwashing facilities in 2019 (World Bank 2021).

Nigeria's health indicators are among the worst in Africa, yet Nigeria has one of the fastest-growing populations in the world. As stated prior, the population of Africa is estimated to reach 1.7 billion by 2030 (Emenike et al. 2017; USAID 2022), and with Nigeria's expected growth, there are bound to be implications on population health indicators of the entire continent of Africa such as infectious disease, environmental quality, and maternal and child morbidity and mortality (Gaffan et al. 2023; ISS African Futures 2023). Therefore, it is important to address population health and development challenges, so that Nigeria has a fighting chance of successfully achieving Sustainable Development Goal (SDG) 6.

Because we did not collect this data on our own or have any input on the kind of data collected, we could not examine potential characteristics that may have influenced the outcome variables in this study.

This study assessed the socioeconomic factors associated with access to improved drinking water sources and sanitation facilities, and HWT in Nigeria. Our findings show that Nigerians living in rural areas, who had no/preschool-level of education, or were poorer, had significantly less access to WASH, either through public works or other forms of water treatment. Findings largely confirm smaller-scale, local- and regional-level studies identifying poverty level, education level, and residence type as important factors in WASH access. Achieving SDG 6 by 2030 will require exceptional efforts, namely increased funding and implementation of policies that support international health efforts such as those discussed prior (i.e., NUWSRP, NAP, etc.). Fortunately, there are ongoing efforts by the Nigerian government. Unfortunately, these efforts fall short as reflected by this study's findings, existing research, and other literature. The government still has a long way to go in developing Nigeria's WASH sector. Support from the World Bank and other development partners is seemingly a vital aspect of moving the needle with regard to financial support, but this is not enough as funding for the WASH sector in particular is weak. The World Bank estimates that Nigeria will have to triple its budget or at least allocate 1.7% of the current Gross Domestic Product (GDP) specifically to WASH alone (UNICEF 2018). The need is highest for rural populations where the gap for improved services is widest.

The Nigerian government should develop targeted approaches that focus on the more socioeconomically disadvantaged populations in order to decrease the disparities in access to improved WASH services and resources. For example, the efforts of the SURWASH program to improve water supply service delivery are primarily focused on institutions such as schools and healthcare facilities. These efforts should be expanded to rural households in Nigeria. To that end, more focus should be placed on HWT interventions – specifically to address the lack of resources that are required to perform HWT, i.e., chlorine, water filters, etc. Because this would be a costly and herculean task, it is advisable that interventions are also focused on more affordable resources that are relatively easier to scale up throughout time, specifically chlorination.

All relevant data are available from an online repository or repositories at https://dhsprogram.com/data/dataset/Nigeria_Standard-DHS_2018.cfm?flag=0.

The authors declare there is no conflict.