N'Djamena, located in the Chari-Baguirmi province, is Chad's political capital and largest city. Established in April 1900 and designated as a district in 1919, it is located on the eastern bank of the Chari River, bordering Cameroon where the Logone and Chari rivers converge. The terrain is predominantly flat, with slight natural slopes. The city spans 39,500 hectares of urbanised areas, divided into ten municipal districts, and boasts a population of 1,390,309 residents, growing at an annual rate of 3.61% as of 2018. N'Djamena experiences distinct seasons, with a dry period from November to April and a rainy season from May to October. The climate registers an average maximum temperature of 44.1°C and a minimum of 23.8°C. Recent years have seen an annual rainfall range from 584 mm to 990 mm. The study primarily focused on the 3rd and 9th districts, positioned between 12°6'0'' and 12°0'0'' North latitude and between 15°2'0'' and 15°10'0'' East longitude. These districts are further divided into thirteen quarters: Ambassatna, Ardep Djoumal, Djambalbarh, Gardolé1, Kabalaye, Sabangali, Digangali, Gardolé 2, Kabé, Ngoumna, Ngueli, Toukra, and WaliaFigure 1

The research process unfolded through a meticulous methodology, encompassing a survey of 395 households, focus group discussions, direct observations, interviews with investigators utilising Android phones, exchanges with the mayors of two municipalities, personnel responsible for Water, Sanitation, and Hygiene (WASH), semi-structured interviews with health district officials, municipal delegates, neighbourhood leaders, institutional actors, and the Chadian Water Company (STE). This approach involved a diverse sample of 57 men, 97 women, 22 teenage girls, 10 male students, and 22 female students. Furthermore, testimonials and life narratives related to waterborne diseases were collected. The analysis of interviews was bolstered by referencing various documents, including reports, laws, legislative texts, Water Code data, municipal decrees, and other relevant research sources. Additionally, epidemiological data for 2019-2022 in the 3rd and 9th districts were obtained by scrutinising the daily consultation records of the Order of Malta Health Centre and the Mother and Child University Hospital. Data collection tools comprised household questionnaires, interview guides for key informants, and an observation checklist. This comprehensive methodological approach facilitated a profound understanding of the challenges and opportunities associated with water, sanitation, hygiene management, and waterborne diseases in the study area. It also promoted gathering diverse perspectives and expertise to enhance our analysis.

This research received approval from the Chad National Bioethics Committee (CNBT) in August 2022. It included a detailed protection protocol outlining potential risks throughout the survey's lifecycle. Verbal consent was obtained from each participant, who was individually interviewed. All participants were fully informed of the voluntary nature of their participation and the confidentiality and anonymity of the provided information. Furthermore, participants were informed of their right to refuse to answer any question, terminate the interview at any time, or even decline to participate in the survey altogether.

Chad has established vital regulations governing national environmental, health, water, and sanitation-hygiene policies. However, the primary challenge lies not in the quantity or quality of these regulations but in their practical implementation and oversight. Several noteworthy and relatively recent documents are particularly relevant to this research.

Law No. 014/PR/98 of August 17, 1998, outlines the fundamental principles of environmental protection, establishes the foundations of the national environmental protection policy, defines the principles of sustainable environmental management, and aims to prevent any degradation. Its objective is to safeguard and enhance natural resources and improve the population's living conditions.

DecreeNo.904/PR/PM/MERH/2009ofAugust6,2009,sets out regulations regarding environmental pollution and nuisances, clearly defining these issues. It also envisions the creation of a national technical committee responsible for monitoring and evaluating the implementation of international agreements related to pollution and nuisances. Furthermore, it establishes a coordination unit to oversee activities related to these issues and a technical control unit whose primary mission is to protect the environment against all forms of pollution and nuisances. Limited material and financial resources hinder the effective implementation of this implementing decree.

Law No. 014/PR/11 of February 28, 2011, establishes the Public Hygiene Code. This code defines the standards regarding environmental hygiene, sanitation of public spaces, food establishments, food items, water, industrial and commercial facilities, residences, swimming pools, educational institutions, healthcare facilities, public and private buildings, as well as the natural environment, even though their implementation remains non-existent due to the lack of adequate sanitary infrastructure enabling monitoring and control in accordance with the standard provisions stipulated in the Public Hygiene Code.

The National Health Policy 2007-2015 was developed, validated, and adopted in May 2007 by all healthcare sector stakeholders and the Ministry of Health and Prevention. It is part of the government's social policy to provide quality healthcare services to the population. It provides healthcare professionals with a vision of healthcare development until 2015, with strategic directions tailored to the country's context. Unfortunately, the financial, material, and human resources did not align with this National Health Policy.

Law No. 16/PR/99 of August 18, 1999, establishes the Water Code, governing the management of river, lake, and groundwater, as well as hydraulic works, as determined by the provisions of this code, subject to compliance with international agreements. All national water resources are a collective asset, part of the state's public domain, inalienable, and imprescriptible. Their exploitation requires authorisation and must comply with existing laws and customary law.

Article 117 stipulates that prior authorisation is required for any action that may alter water quality. This code includes several sections dealing with sanitation. Historically, sanitation has been considered a complementary measure, implemented as part of other activities, such as disease control or the establishment of drinking water supply programs. However, the necessary material and financial resources are not always allocated adequately to ensure its effective implementation.

Decree No. 615/PR/PM/ME/MSP/2010 of August 2, 2010, defines quality standards for water intended for human consumption in Chad. Its purpose is to protect health by preventing adverse effects related to unsafe water. It applies to all water intended for human consumption in the Chadian territory, including bottled or other containers, except in certain circumstances. This decree does not cover natural mineral waters. Article 4 specifies that drinking water for human consumption must not harm consumers' health. It must not show signs of physicochemical, bacteriological, or biological pollution or contain toxic substances exceeding the standards established in the annexe to the decree. This decree is ineffective due to a lack of continuous monitoring of water quality: strict standards, treatment, awareness, and collaboration with health authorities to ensure the safety of drinking water.

The Decree No. 330/PR/PM/MEH/2010 of January 20, 2015, establishing the modalities for the transfer of state competencies to decentralised territorial authorities concerning the delegation of the public water service, has not been fully effective across the entire territory due to the absence of adequate accompanying measures.

The Drinking Water and Sanitation Master Plan (SDEA), established and adopted on April 30, 2003, with the support of UNDP-DAES, aims to achieve the access rate to potable water defined by the MDGs. However, this objective has not been achieved due to insufficient resources.

The N'Djamena City Hall issued two significant municipal orders to improve sanitary conditions in the city: Municipal Order No. 146/SG/DSTM/SUHA/96 of October 18, 1996, making the construction of family latrines mandatory, and MunicipalOrderNo.037/M/SG/DSTM/SHS/04ofFebruary17,2004, regulating the management of domestic, sewerage, and industrial wastewater in the municipality of N'Djamena. These two orders have not yielded the desired results in changing the population's behaviour because no preparatory activities were undertaken beforehand for their implementation. For example, awareness campaigns, mobilisation, accompanying measures, monitoring, evaluation, and material and financial resources are lacking or limited.

MunicipalOrderNo.145/M/SG/DSTM/SUHA/96ofOctober18,1996,prohibits open defecation. The real factors hindering the enforcement of this order include a lack of adequate sanitary infrastructure, insufficient hygiene awareness and education, financial constraints for the construction of proper toilets, and implementation issues due to a lack of proper oversight and sanctions.

Article 3 of this ordinance outlines its fundamental principles. It states that any natural or legal person who produces or holds waste in conditions that may harm the soil, flora, or fauna, alter landscapes, pollute the air or water, generate noise or odours, and, in general, harm human, animal, and environmental health, is obligated to ensure or have ensured their disposal in accordance with the provisions of this law. However, this ordinance has implementation issues due to a lack of proper monitoring and adequate sanctions.

The Constitution of the Republic of Chad underscores the importance placed on safeguarding human health, the environment, water resources, sanitation, and hygiene. Dated March 31, 1996, and subsequently revised in 2005, 2018, and 2020, it explicitly lays out the following principles:

· Every individual has the right to a healthy environment (Article 47) ;

· The State and decentralised authorities have to ensure environmental protection (Article 48) ;

· The transportation, importation, storage, disposal, or discharge of toxic or polluting substances are strictly prohibited in Chad.

The rigorous implementation of laws and regulations governing environmental protection, water, hygiene, and sanitation will significantly contribute to public health protection and the sustainable preservation of our environment while enhancing food security for the population. This will involve the collection and treatment of solid waste, faecal matter, secure wastewater, and rainwater, as well as the treatment of industrial wastewater, thereby ensuring water security. Furthermore, information campaigns on the Hygiene Code, implementing decrees, and establishing a health police force will be necessary to safeguard the population against waterborne diseases and other health risks. These efforts must be undertaken with determination and consistency to ensure a healthier future for all.

Waterborne diseases arise due to deteriorating hygiene and sanitary controls 41. These illnesses can be triggered by various microorganisms, such as bacteria, viruses, and parasites 64.

"Water-related diseases" refer to those contracted through ingestion or direct contact or diseases in which water is the habitat for larvae or parasites 94. Categorising water- induced diseases is crucial for assessing public health risks, aiming to classify and understand diseases related to water contamination, whether by pathogens, chemicals, or other contaminants 60. These diseases can have severe consequences for human health, and their categorisation is essential for implementing effective water management, prevention, control, and treatment strategies. However, these diseases can be broadly classified into three categories based on their health implications concerning water: waterborne diseases, vector-borne diseases linked to water, and waterborne-origin diseases 65.

Waterborne diseases, or water-related illnesses, are infections caused by the consumption or contact with water contaminated by pathogens such as bacteria, viruses, parasites, or other microorganisms 8. They pose a significant health concern in many regions of the world, especially in developing countries where access to safe drinking water is limited and often associated with poor hygiene and sanitation conditions 133. Preventing waterborne diseases involves improving the supply of clean drinking water, ensuring proper sanitation facilities, educating people about personal hygiene, and administering vaccines when possible 36. Treatment depends on the specific disease but may include rehydration, the administration of antibiotics or antiparasitic drugs, and other supportive measures 21. It is important to note that waterborne diseases can be deadly, especially in malnourished individuals or those with weakened immune systems (Ali, 2023). Therefore, proper prevention and management are essential to reduce the impact of these diseases on public health.

Water-related vector-borne diseases are infections caused by pathogens such as bacteria, viruses, or parasites that are transmitted by aquatic organisms, such as mosquitoes,flies,fleas, or mollusks117. They remain a significant challenge in many regions, particularly developing countries where access to clean water and sanitation is limited 112. Diseases like malaria (transmitted by the Anopheles mosquito) and dengue (transmitted by the Aedesmosquito) continue to inflict considerable suffering, with these vectors finding their breeding grounds in aquatic environments 79. Changes in habitats and climatic conditions can promote mosquito proliferation and the spread of these diseases 19. It is important to note that the prevention and control of these diseases often depend on improving access to clean drinking water, vector management, sanitation, and health education 35. This study will be limited to waterborne diseases. Table 1

The section aims to elucidate the concept of water-origin diseases and assess their severity in developing nations. The National Institute of Public Health of Quebec defines water-origin diseases as infectious or physicochemical ailments caused or presumed to be caused by water ingestion, contact, or inhalation. Pathogenic microorganisms like bacteria, viruses, parasites, and protozoa are common culprits, spreading through contaminated water, skin contact, or ingesting food prepared with untreated water 104. Populations lacking access to safe water, sanitation, and hygiene practices are particularly vulnerable, as untreated faecal matter can contaminate freshwater sources and food 62. Notable water-origin diseases include cholera, typhoid, polio, dysentery, diarrhoea, and hepatitis A and B. Humans and animals host these pathogens 119.

The World Health Organization reports that around 2 billion people globally rely on water contaminated by faecal matter, posing a substantial risk to public health. Water-Origin Diseases are a significant challenge in developing countries, leading to high morbidity and mortality, especially among children under 5. Diarrheal diseases, with an estimated 1.7 billion cases annually, rank as the second leading cause of death in this age group worldwide 119. Developing nations bear the brunt, with 18% of under-five deaths attributed to these diseases, predominantly in Africa and Southeast Asia 123. Poor water quality and inadequate sanitation result in approximately 297,000 annual deaths in children under 5 due to diarrheal diseases 86. Disposing of human waste in open areas exacerbates the issue, contributing to microbiological contamination of water 126. Crucially, prevention hinges on enhancing access to clean water and adopting proper hygiene and sanitation practices. Addressing these challenges is vital to curbing the impact of water- origin diseases and improving public health in vulnerable communities.

Waterborne diseases primarily spread through drinking water or surface water contamination by pathogens (bacteria, viruses, parasites, chemicals) 77. Transmission pathways include ingesting contaminated water, skin contact, consuming contaminated food, exposure to wastewater, transmitting through vectors such as flies, and lacking personal hygiene 94.

The key factors contributing to the proliferation of waterborne communicable diseases

The main factors contributing to the proliferation of waterborne diseases include: Household hygiene: Poor hygiene in both individual and collective settings in disadvantaged areas facilitates pathogen transmission 32117 Socioeconomic status of households: Precarious living conditions, such as overcrowding and close quarters, increase the risk of contagion 129; Community living (markets, churches, hospitals, etc.): Gatherings in these environments can promote disease spread without adequate hygiene and prevention measures 131 Quality of the drinking water supply network: Inadequate control of distributed water can lead to pathogen contamination 56; Limited access to safe drinking water: Using untreated water raises the risk of waterborne diseases 78; Inadequate water treatment and monitoring: Poor water treatment and insufficient quality monitoring expose the population to health risks 57; Lack of health education: Insufficient awareness about personal hygiene, water purification, and environmental health also contributes to disease transmission 142 Overpopulation and population density: High population density can facilitate disease spread due to inadequate healthcare infrastructure to meet the population's needs 38117; Failures in pumps, pipelines, and water purification facilities can expose populations to risks of waterborne diseases 78; The lack of hygiene in washing vegetables and fruits before consumption, coupled with persistent community conflicts associated with certain beliefs and practices, are major factors contributing to the transmission of waterborne diseases 1524.

The environmental impacts of hygiene, sanitation, and sanitary practices are a major global concern, leading to significant repercussions on public health and the planet's sustainability 88. Within the study area, observations reveal substantial quantities of solid and liquid waste scattered in streets, open spaces, gutters, and depressions. Among these wastes, biodegradable materials such as plant debris, leaves, branches, food remnants, and non- biodegradable items like plastic bags, packaging, tin cans, and glass bottles negatively affect the environment 33. Furthermore, the presence of faecal matter in depressions, open spaces, and unregulated dumps, along with the untreated discharge of domestic wastewater and flush toilet effluents into stormwater drainage channels, intensifies soil and groundwater contamination, compromising water quality and biodiversity 4. These wastes also detrimentally affect the living environment by emitting foul odours, while the proliferation of insects and rodents threatens residents' health (Suare Marcillo, 2012). Waterborne diseases, stemming from various factors such as contamination of drinking water, non-adherence to hygiene practices, the use of communal toilets, and the disposal of anthropogenic waste into water, spread throughout the districts 118. Faced with these challenges, it is imperative to implement sustainable solutions involving effective management of potable water supply systems, improved hygiene practices, safe waste collection and disposal, promotion of modern sanitation facilities, and raising awareness of chemical risks. These measures will contribute to preserving public health and the environment, maintaining optimal sanitary conditions.

Unsafe water pollution has severe consequences on human health. According to the UNESCO World Water Development Report in 2021, approximately 829,000 people lose their lives annually due to waterborne diseases caused by non-potable water, lack of sanitation, and poor hand hygiene 25. Among these deaths, nearly 300,000 are children under the age of five, accounting for 5.3% of all deaths in this age group 13. However, in the study area, almost the entire population (99.8%) exclusively consumed water from taps and hand-powered pumps (PMH). The quality of this water is mainly compromised by the contamination of two physicochemical parameters (temperature and ammonium) and two bacteriological parameters (total coliforms and total aerobic flora), leading to a high prevalence of waterborne diseases. Furthermore, concerning tap water consumption, purified water, and bottled water, it has been established that tap water is a significant source of gastrointestinal diseases 80122, hindering nutrient absorption and causing malnutrition 113. These findings align with those in Palestine, where individuals consuming municipal water directly face a higher risk of waterborne diseases such as diarrhoea than those using desalinated and filtered drinking water at the household level 5. These effects are particularly pronounced in children 124. According to epidemiological data from 2019 to 2022 obtained from the Order of Malta Health Centre in Wallia and the Mother and Child University Hospital in Gardolé, a significant

prevalence of water-related diseases has been recorded among women of childbearing age and children aged 0 to 5. These diseases primarily include diarrhoea (3948 cases), dysentery (2908 cases), skin infections (650 cases), typhoid (1953 cases), abdominal pains (1250 cases), and malaria (21096 cases). It is also concerning to note the number of deaths associated with these diseases, including 267 deaths from severe malaria, 69 deaths of gastrointestinal origin among children aged 0 to 5, and 103 deaths due to typhoid fever. Pathogens can also transmit these diseases from inadequate sanitation facilities, unfavourable piping conditions, and water supply system architecture conducive to the growth of microorganisms 110, even within the microbial communities present in drinking water distribution systems, leading to waterborne diseases 56. Consumption of contaminated water, open defecation, ruptures, or leaks can trigger low-pressure events, and when repaired, pathogens can enter the systems 4076. Additionally, the lack of adequate services for the disposal of faecal matter, solid and liquid waste, and climatic conditions plays a crucial role in epidemics 78. Climate can introduce contaminants into water sources through runoff during intense precipitation or floods 147. Moreover, temperature variations ranging from 30-45 °C can alter the dynamics of microbes in pipelines, and pathogens present can be released into moving water 20, along with inadequate hygiene practices. All these factors support the obtained results, revealing that most surveyed households attribute these diseases to poor drinking water quality (50%), inadequate hygiene practices (28%), and unsanitary conditions (19%). In comparison, others (3%) could not provide a specific response to this question.

These two districts face inadequate healthcare systems due to various socio-economic reasons. Thus, this area will bear a heavy burden in terms of morbidity by the end of 2022, with an observed increase in cases of waterborne diseases. Unfortunately, most of the budget allocated to the health, water, and sanitation sectors is mainly invested in poorly designed or unfinished water projects, leading to groundwater pollution 109. Moreover, a significant portion of these funds is allocated to purchasing medications and operating various technical services 37. However, the misappropriation of public funds has reached alarming levels in this environment 94. Preventive measures have not been implemented, such as hygiene promotion, mobilisation, awareness, and accompanying actions to alleviate the populations affected by these diseases 124. Furthermore, collaboration to reduce or eradicate high-morbidity waterborne diseases has not been undertaken between different districts of the city of N'Djamena in partnership with development actors. A more coordinated approach and cooperation between districts and stakeholders could significantly mitigate this urgent public health issue 142.

Adhering to the following recommendations can significantly mitigate or eliminate the risk of waterborne communicable diseases:

In the study area, drinking water treatment poses a significant challenge due to limited resources and constraints on access to energy for boiling-based disinfection. Therefore, we advocate and strongly encourage the adoption of simpler, cost-effective, and less energy-intensive alternative techniques.

Ensuring a safe and clean water supply is the most crucial preventive measure to reduce the risk of waterborne diseases 41. Free chlorine has proven to be the most widely used and practical disinfectant for purifying water intended for human consumption 82. It is an effective and cost-efficient method for eliminating pathogenic microorganisms in water, such as bacteria and viruses, except for Cryptosporidium spp and certain species of mycobacteria (Bloom & Reenan, 2013). Adding just a few milligrams of free chlorine per litre of water for about thirty minutes generally inactivates nearly 100% of enterobacteria and viruses 52. In addition to disinfection, chlorination can also contribute to maintaining water quality by preventing the growth of algae and bacteria in drinking water distribution systems 56. This helps prevent biofilm formation and ensures clean water throughout the distribution network 144. However, it is crucial to monitor and manage the process to minimise undesirable effects, such as by-product formation 105. When chlorine reacts with organic matter in water, it can produce by-products such as trihalomethanes (THMs), which can harm health at high concentrations 82. Thus, ensuring the supply of high-quality drinking water requires careful management of these processes.

These WHO guidelines may vary depending on local conditions, water characteristics, and other factors. Table 2

Exposing drinking water to sunlight for several hours (typically 6 hours) can destroy bacteria, viruses, and parasites 70. This can be achieved using transparent plastic bottles filled with water 120.

Water filters prevent waterborne diseases by removing contaminants and making drinking water safer 35. Using activated carbon or membrane filters can render water potable and safe for consumption 87. Therefore, to ensure that water remains clean and safe for drinking, it is essential to store it in suitable containers equipped with taps to prevent any subsequent contamination 23. It is important to note that the effectiveness of water filters can vary depending on the quality of the water source and regular filter maintenance 43. It is highly recommended for health authorities and water management experts in municipalities to conduct a thorough assessment to determine the most suitable filtration system 44. Furthermore, the selected filters must be certified to meet the water quality standards established by the World Health Organization and the national guidelines of Chad.

The filter featured in Figure 2 is available in certain outlets and is occasionally offered at affordable prices in local markets in Ndjamena. We recommend promoting, subsidising by the government, and utilising it in the study area after the health regulatory services approve it.

Moringa seeds, a common plant in the study area, can be used for water decontamination 47. Crushed moringa seeds can be added to water to act as a natural coagulant, removing suspended particles 121Figure 2

The grant or free distribution of water containers, cooking pots, and fuel in sufficient quality and quantity to the most impoverished households should play a significant role in reducing the risk of diseases such as typhoid fever, dysentery, diarrhoea, and more. This would ensure the preservation of stored clean water and the proper preparation of food 66.

To monitor and collect data on drinking water quality provided by the Chadian Water Company (STE), it is imperative to establish a real-time monitoring system for water quality indicators using sensors 112. These sensors should be installed at the most frequently used water fountains 143. The data collected will then be used to quickly detect abnormal fluctuations in water quality, allowing for effective intervention in resolving the issue of drinking water contamination 74. For frequently used human-powered pumps (HPPs), municipalities should be equipped with portable rapid analysis kits to determine precisely the water quality consumed by households in their jurisdictions 131. This will require training WASH agents, well operators, and water point managers on sensor data handling and interpretation and using these portable analysis kits 67. Based on the collected data, targeted interventions can be planned, such as water treatment, water point disinfection, distribution of hygiene kits, geolocation of clean water distribution points, and identification of high-risk areas 71. Based on the collected data, targeted interventions can be planned, such as water treatment, water point disinfection, distribution of hygiene kits, geolocation of clean water distribution points, and identification of high-risk areas 91. Regular meetings should be organised to plan and coordinate interventions, including the temporary or permanent closure of heavily polluted or contaminated water points, among other measures 46 . Additionally, municipal authorities must routinely monitor drinking water quality and take immediate action to address identified issues.

Health education is vital in preventing and eradicating water-related diseases in our study area, which faces significant health challenges due to the quality of drinking water and sanitation 12. To combat these diseases effectively, it is imperative to raise awareness among the population about good hygiene practices, proper sanitation, and responsible water management 142. Here are some key points to consider:

Households need to be informed about the risks associated with consuming untreated water from unreliable sources like the Logone and Chari rivers and the benefits of having access to safe drinking water 72.

Personal hygiene and waste management are crucial to prevent waterborne diseases 78. Educational programs should promote using latrines, proper excreta disposal, and regular handwashing, especially before meals and after using the toilet 126. Disinfecting excreta with cresol sodium without a sewage system and fly control is a vital concern for hygiene and public health 90.

Training healthcare professionals and local peer educators is essential to disseminate water health knowledge effectively 145. They can convey accurate information and raise community awareness 54.

Radio, television, and social media should be harnessed to disseminate health education messages on clean water, sanitation, and hygiene 95. Well-crafted media campaigns can reach a broad audience 63.

Active involvement of residents in planning and implementing health education programs is crucial, as households must be encouraged to improve their health conditions by taking responsible steps for positive behaviour change 11.

Collecting data on hygiene practices, waterborne disease rates, and progress in implementing health education programs is crucial to measuring the impact of interventions and making necessary adjustments 50. Health education will be vital in combating waterborne diseases 31. Providing accurate information and promoting proper hygiene practices can significantly reduce the spread of these diseases and improve the quality of life for vulnerable populations 61. However, this approach must be supported by investments in water infrastructure and sanitation to achieve sustainable results 41. Table 3

The STE and the personnel responsible for water supply and sanitation in municipalities must ensure compliance with hygiene standards at water distribution points and fountains following the requirements specified in the contract with water point operators in all districts 107. Municipal authorities responsible for WASH should incorporate water code requirements into company contracts 67. These requirements should become critical elements from the infrastructure design and construction phase, such as small-scale water supply systems and sanitation facilities 115. This approach will ensure the effective implementation of water-related standards and regulations, delivering high-quality WASH services to households 27. Municipal authorities should enhance the skills of water supply technicians and well managers in sanitation and water hygiene to maintain the quality of drinking water produced 67. Establishing ongoing cross-sector collaboration, particularly between the fields of hydraulics and health, is of paramount importance. Active involvement of municipalities remains essential for achieving these objectives 41. Standardising the technical inspection methods employed in the hydraulic sector, including an online component for accessing these standards and procedures 92.

The study area is facing significant challenges in managing excreta and wastewater. These challenges are exacerbated due to its rapid growth and urbanisation, necessitating an innovative and sustainable approach to address this issue 107. That is why we propose the condominium network. The condominium network is a wastewater management system that collects, treats, and reuses wastewater at the neighbourhood level 30. It is an integrated approach that efficiently and cost-effectively manages excreta and wastewater, with the potential solution being implementing condominium wastewater management networks while minimising environmental impacts 68.

Key advantages of the condominium network compared to the conventional model include:

Efficient collection of wastewater using an underground pipeline network;

Treatment of collected wastewater locally in treatment plants tailored to the population size served 51

Reuse of treated water for irrigation, landscaping maintenance, or safe discharge into the environment, contributing to water resource conservation 34.

More cost-effective to implement and maintain, making it more accessible for rapidly growing urban communities 3.

Community participation: Encourages active involvement of residents in the system's management and maintenance, strengthening a sense of community responsibility and ownership 26.

Each block comprises 30-40 households 48.

The operation of this system will be the responsibility of autonomous municipalities led by a Condominium Committee, and its maintenance will be ensured by the same committee 127.

Responsibilities for solid waste management include collection, sorting, recycling, and environmentally responsible disposal of waste 34. Municipal authorities must establish adequate infrastructure, such as sorting centres and sanitary landfills, and develop regulations to encourage source reduction and public awareness 84. In the case of excreta and wastewater, ensuring proper sanitation systems is essential 106. This includes constructing and maintaining sewage networks and wastewater treatment plants and promoting improved household toilets 45. The primary responsibility in this area also falls on local authorities, working in collaboration with public health stakeholders, to establish the following coordination and management structure 28.

Securing funding for these initiatives is a substantial challenge. The study area is proposed to explore various funding sources, including government funds such as budgetary support and municipal grants 108. Public-private partnerships focusing on sanitation projects and support from NGOs and associations are also viable options 42. Another avenue is seeking international grants from organisations like AFD (French Development Agency) and BAD (African Development Bank). Creating a dedicated fund for sanitation management is also suggested 115. This fund could be fuelled by diverse means, including waste and habitat taxes, infrastructure usage fees, and voluntary contributions from businesses and citizens 83. This diversified approach would mobilise varied financial resources, ensuring a robust foundation for the sustainable financing of sanitation initiatives 18. Table 4

Waterborne diseases pose a significant public health challenge in Chadian cities, affecting children aged 0-5 years and the entire population, irrespective of social class (Guarango, 2022). Their impact is reflected in high annual prevalence rates, hospitalisations, and, unfortunately, fatalities. The coordinated and sustainable management of waterborne diseases in healthcare centres and hospitals 103, especially in vulnerable areas like the 3rd and 9th districts of N'Djamena, requires the implementation of effective institutional strategies, despite limited resources, to mitigate their impact on public health 39. Here are some suggested solutions:,Table 5

Due to the high prevalence of waterborne diseases in the study area, it would be desirable for households to be vaccinated per the 141 recommendations. These guidelines emphasise the crucial role of vaccinations against waterborne diseases in preventing potentially severe infections 77. Figure 3

Cholera: The oral cholera vaccine (OCV) and Vaxchora are recommended 77.

Typhoid: The injectable Typhim (Vi) and the oral Vivotif (Ty21a) vaccines are recommended 77.

Polio: The oral attenuated virus vaccine (OPV) and the inactivated vaccine (IPV) have played a significant role in nearly eradicating the disease 29.

Hepatitis A: The vaccine against hepatitis A (Avaxim, Epaxal, etc.) is recommended 146. Figure 5

Hepatitis B: The vaccine against hepatitis B (Engerix-B, Heplisav-B, etc.) is recommended 69. Figure 4