Bukavu is a city located in the eastern part of the Democratic Republic of the Congo (DRC), situated on the southwestern shore of Lake Kivu ( Figure 1 ). Positioned at an altitude ranging from 1460 meters (lake level) to 1900 meters (Kadutu summit), it serves as the administrative center of the South Kivu province. The city shares a border with Rwanda, demarcated by the Ruzizi River and Lake Kivu ( Lina, 2016 ).

Administratively, Bukavu is divided into three municipalities: Ibanda, Kadutu, and Bagira. These municipalities cover a total area of 63 km², of which 20 km² is water surface on the lake ( Kalikone et al., 2017 ). Kadutu was the first of the three municipalities established in Bukavu. It hosts the largest market in Bukavu, numerous schools, a university, and the city’s largest hospital. Overall, the city contains a total of 11 markets ( Kalikone et al., 2017 ).

In 2020, the city of Bukavu had an estimated population of approximately 1.3 million, resulting in a population density of about 30,000 inhabitants per square kilometer. Based on projections with a growth rate of 4.1%, the population is expected to reach 1,942,901 by 2030 and 2,375,222 by 2035 ( Lina, 2016 ).

The study was based on the hypothesis that in the city of Bukavu, there is a significant correlation between the use of non-collective sanitation and hygiene-related diseases. To test this hypothesis, we employed two data collection techniques: documentary research and field data collection (observations and questionnaire surveys conducted with household heads). The questionnaire survey gathered information on the geolocation and characteristics of sanitation types, household attributes, perceptions, challenges, and health issues among the population of Bukavu. A total of 1210 household heads were surveyed between October 15 and November 18, 2023, across 17 neighborhoods, taking into account the specific characteristics and geographical locations of the neighborhoods.

For data collection, the tablets were configured by installing the Kobo Collect application. The city of Bukavu is estimated to comprise 216,327 households, and for each surveyed household, only one individual was considered. Regarding household selection, a random targeting approach was employed to ensure comprehensive coverage of the sampling frame. The distribution of households to be surveyed within each neighborhood was proportional to the total number of households in that area. The sample size was calculated based on the formula provided by Rea and Parker (2014) :

$n=\left(t_p^2\ast P\left(1-P\right)\ast N\right)/\left(t_p^2\ast P\left(1-P\right)+\left(N-1\right)\ast y^2\right)$(1)

where n = sample size; N = target population size (number of households); P = expected proportion of responses from the population; t_p = sampling confidence interval; and y = sampling margin of error. Accordingly, with n representing the sample size and N the total number of households, the sampling interval t_p was determined for each neighborhood using the formula t_p = N/n. The first household was randomly selected within the interval [1, t_p], while the remaining households were chosen following the predetermined sampling step, as calculated above (systematic sampling). In other words, the sampling fraction was iteratively added to the randomly selected starting point. In cases where a building had multiple apartments on different floors, only one household per building was included in the sample.

Given the possibility of errors or incomplete forms during the survey, we increased the sample size by 5%. The total number of households surveyed was 1210. Based on the percentage distribution of households in each commune of Bukavu, we surveyed 290 households (24%) in the Bagira commune, 520 households (43%) in the Ibanda commune, and 400 households (33%) in the Kadutu commune.

The data collected from survey forms and interviews were entered into an SPSS version 16 database. The analysis initially involved interpreting respondents’ opinions, with proportions determined by calculating percentages. Subsequently, cross-tabulations of different variables were conducted using SPSS version 16 to identify potential dependencies between two variables. Pearson’s Chi-square test was applied to assess deviations from independence.

According to the distribution of household living standards in the city of Bukavu, Bagira primarily hosts middle-income households, accounting for 82.3%, while 17.7% belong to the low-income category ( Figure 2 ). The Ibanda municipality is predominantly characterized by high-income households, comprising 74.1%, with middle-income households making up 25.9%. In contrast, the Kadutu municipality is mainly populated by low-income households, which represent 89.5%, while middle-income households account for 10.5%.

The majority of housing units (66%) are occupied by owners, 21% by tenants, and 13% are provided without charge ( Figure 3 ).

The majority of households in the Bagira commune predominantly use manually flushed latrines (47%), whereas the use of modern toilets and pit latrines is significantly more prevalent in the Ibanda (67%) and Kadutu (70%) communes, respectively ( Figure 4 ).

In the city of Bukavu, 61.4% of households in Bagira and 35.8% of households in Kadutu discharge their wastewater into drainage ditches, whereas over 69.8% of households in Ibanda discharge into seepage wells ( Table 1 ).

Chi-square tests of Pearson: 164.524^a, Likelihood ratio 195, 729; ddl: 8, p < 0.05.

The survey conducted in the three municipalities reveals that the common disposal sites for emptied materials are as follows: constructed pits (65%), nearby canals (20%), and various other locations such as rivers and lakes (15%) ( Figure 5 ).

The results obtained from our respondents indicate that 47% of our sample assert that the incivility of the population is the primary cause of the inadequate management of waste in the city of Bukavu. This is followed by unregulated construction and the lack of state involvement, each representing 18% of the sample size ( Figure 6 ).

The findings obtained ( Figure 7 ) from our survey indicate that 56% of the respondents recognize that inadequate management of wastewater and excreta contributes to the proliferation of diseases in the city of Bukavu. This highlights a significant level of awareness among the population regarding the public health risks associated with poor sanitation practices

The results obtained in the city of Bukavu indicate that over 60% of households are owner-occupied, while less than 15% are tenant-occupied ( Figure 3 ). This parameter is significant as it provides insights into the sanitary conditions of their homes, given their relatively long-term residence. Additionally, it would be relatively easier to encourage these homeowners to invest in improving their wastewater and excreta treatment facilities ( Lina, 2016 ).

The findings of this study are consistent with those of Nyakpo (2022) in the city of Vogan, where 53.42% of households were owner-occupied, 16.44% were occupied by family members of the owner, and 30.14% were tenant-occupied.

For social categories ( Figure 2 ), the Bagira commune predominantly hosts middle-class households (82.3%), Ibanda is mainly occupied by high-income households (74.1%), and Kadutu by low-income households (89.5%). The majority of households in Bagira commune use manual flush latrines (47%), while modern toilets and pit latrines dominate in the Ibanda (67%) and Kadutu (70%) communes, respectively ( Figure 4 ).

This indicates that household income influences the type of toilet facilities installed in homes. High-income households tend to install septic tanks, while low-income households rely on traditional or pit latrines. The latter pose significant health and environmental risks and should be replaced with facilities that are more health- and environmentally-friendly ( Aissi et al., 2023 ).

Traditional latrines do not provide a barrier between the user and excreta. Populations using such facilities are not considered to have access to adequate sanitation as per the Sustainable Development Goals (SDGs). It is therefore crucial to support these populations in acquiring sanitation facilities that ensure reliable health and environmental protection. Otherwise, the situation risks becoming more chaotic by the SDG deadline ( Nguea, 2024 ).

These findings align with those of Bagalwa Nyamugara (2024) , who reported that 69.3% and 47.3% of high- and middle-income social categories, respectively, used modern toilets with septic tanks. In contrast, low-income households predominantly used traditional latrines (41.3%) or pit latrines (36%).

Regarding the common sites for the disposal of wastewater and septic sludge, survey results ( Figure 5 ) indicate that septic sludge is primarily discharged into designated pits (65%), nearby drainage channels (20%), and rivers and lakes (15%). As for wastewater ( Figure 1 ), over 60% of households in Bagira and more than 80% of households in Kadutu discharge their wastewater into drains, while over 65% of households in Ibanda release their wastewater into leach pits.

The cross-tabulation percentages represent the occurrences where each municipality discharges its wastewater ( Table 1 ). The data reveal that all municipalities discharge wastewater into drainage channels, with Bagira (middle-income) leading, followed by Kadutu (low-income). Notably, in Kadutu, soak pits are also used for wastewater management, whereas in Ibanda (high-income), wastewater is predominantly discharged into rivers. Pearson’s Chi-square test yielded a high coefficient of 164.524, with a Likelihood Ratio of 195.729 for 1210 valid observations. These results indicate a statistically significant difference (p < 0.05) in wastewater discharge locations across the municipalities of Bukavu.

The current wastewater and septic sludge management practices in the city of Bukavu have significant public health and environmental consequences. They notably contribute to the pollution of water bodies that could potentially be used for drinking. The high prevalence of malaria could be attributed to the development of mosquito larvae in stagnant wastewater pools ( Kawata et al., 2024 ). Diarrheal diseases and intestinal parasitoses are likely caused by the ingestion of pathogens due to poor sanitation conditions ( Ya Lubo Shabantu et al., 2021 ). Ensuring better management of wastewater and excreta would help improve the health of the population in the city of Bukavu ( Aissi et al., 2023 ).

These findings reinforce those already reported by Isidore et al. (2022) in the Kadutu commune, which indicate that the so-called “other” practice involves discharging the contents of septic tanks into rivers or drains, both of which rely on manual emptying. It is important to note that these practices have harmful health and environmental consequences. The city of Bukavu lacks a sludge treatment facility. The majority of households are unaware of the existence of a sludge treatment station, which results in a situation where sludge emptiers discharge the waste anywhere, disregarding any protective measures for the surrounding population and the receiving environment.

The survey results presented on Figure 6 indicate that 47% of our sample identify public incivility as the primary cause of poor excreta management in the city of Bukavu. These findings align with those of Isidore et al. (2022) in the Kadutu municipality. Other cited causes include anarchic construction and the lack of state involvement, each accounting for 18% of the responses.

Despite this, 56% of respondents acknowledge that poor wastewater and excreta management leads to the proliferation of diseases in Bukavu, a result consistent with the findings of Lina (2016) in the same city. It is important to note that untreated wastewater contains various excreted organisms, including pathogenic agents. To address this issue, it would be essential to implement public information, awareness, and environmental education programs, while also enforcing legal regulations when necessary ( Singh et al., 2021 ).

Studies have also supported the conclusion that proper wastewater management practices effectively reduce diarrheal diseases ( Shukla et al., 2023 ). In several countries, wastewater and excreta treatment and valorization are now mandatory to improve sanitary conditions. Various reuse options are available depending on the treatment processes, including agricultural irrigation, recreational and municipal reuse, groundwater recharge, aquaculture, and land application. However, these applications require water quality standards appropriate for each specific use ( Nasim et al., 2022 ).