Environmental experts and urban planners are calling for decentralised sewerage systems to address Kigali’s growing sanitation challenges, arguing that the city’s hilly terrain and expanding settlements make reliance on a single centralised network impractical. The proposed approach would involve treating wastewater within individual neighbourhoods, housing estates or commercial clusters instead of transporting it through extensive pipelines to one central treatment plant. The recommendation comes amid delays in implementing Kigali’s 92-kilometre Centralised Sewerage System, designed to channel wastewater to a treatment plant at Giti Cy’Inyoni with a daily processing capacity of 12,000 cubic metres. The contractor awarded the project failed to fulfil its contractual obligations, according to the Ministry of Infrastructure. Construction was scheduled to begin in August 2023 and conclude in February 2026, but the contractor missed the deadline despite an extension to March 2026. The delays have compounded sanitation concerns in a rapidly expanding city where some buildings and households discharge wastewater into drainage channels and water bodies. A City of Kigali inspection identified sanitation and wastewater management faults in at least 82 of 128 buildings inspected. Authorities also closed the Parking Car Garage in Nyabugogo after discovering that it was discharging wastewater from toilets into the Mpazi drainage channel. ALSO READ: Govt considering new contractor for Kigali’s sewage system Why decentralised systems? Waste-management expert Paulin Buregeya says Kigali needs smaller sewerage networks serving individual neighbourhoods, commercial areas and settlements rather than relying exclusively on one centralised system. He argues that such networks could address two major challenges: the risk of underground wastewater tanks collapsing in fragile soils and the high cost of transporting sewage across Kigali’s hilly terrain. Buregeya cited Kanombe and the area commonly known as ‘’Kuri 15’ as examples of locations that would be difficult and expensive to connect to the Giti Cy’Inyoni treatment plant. He proposed involving property owners in financing local systems, noting that households already pay between Rwf100,000 and Rwf300,000 to empty septic tanks. Environmental health expert Abias Maniragaba similarly argues that Kigali’s topography makes a single citywide network impractical. “A single sewage system would require expensive pumps due to slopes ranging from 45% to 50%. Kigali has approximately five catchments, so separate systems that rely on gravity flow are more practical,” he said. ALSO READ: Why Kigali’s central sewerage system delayed Maniragaba added that environmental impact assessments would be essential before developing the proposed infrastructure, particularly given concerns about underground septic tanks and landslide risks. What urban planners recommend Vivien Munyaburanga, President of the Rwanda Urban Planners Institute, says Kigali should organise its sewerage infrastructure around hydrological catchments rather than administrative boundaries. He explained that wastewater can flow downhill naturally within a catchment, but transporting it across ridges into another catchment requires pumping stations, electricity and extensive excavation, significantly increasing construction and maintenance costs. “Several catchment-based systems are therefore the right direction,” he said, noting that WASAC indicated in 2025 that Kigali would be divided into three sewerage catchment zones. However, Munyaburanga cautioned that sewerage infrastructure alone would not resolve the city’s sanitation challenges. “Because most households will remain unsewered for the next 15 to 20 years, faecal sludge management must be treated as an equal priority,” he said. According to Munyaburanga, approximately 95 per cent of Kigali households rely on on-site sanitation systems, making improved septic tank management and sludge treatment essential. He recommended developing a Rwandan standard for simplified sewerage and testing it in both a steep, densely populated neighbourhood and a planned housing estate before finalising the redesign of Kigali’s centralised network. The urgency is reinforced by population density: 17 of Kigali’s 35 sectors already have more than 5,000 inhabitants per square kilometre, according to the 2024 faecal sludge management baseline assessment. ALSO READ: Lack of central sewerage system a time bomb Munyaburanga also called for clear policies governing household connections, including whether connections should be mandatory, how costs would be financed and whether social tariffs should support low-income households. Lessons from other cities Munyaburanga cited several international examples that could inform Kigali’s approach. Kampala organises its sewerage infrastructure around wastewater catchments and combines sewage and faecal sludge treatment at Lubigi, while Brazil has adopted simplified sewerage networks in both affluent and informal settlements to reduce infrastructure costs. Japan determines whether areas should receive conventional sewers or decentralised treatment based on lifetime costs, while Durban in South Africa distinguishes between areas suitable for conventional networks and those better served by managed on-site sanitation. He also cited Ethiopian capital, Addis Ababa, where a 2023 study found that the Kality wastewater treatment plant operated below capacity partly because many households had not connected to the system. The examples underscore the importance of planning sewerage infrastructure alongside affordable household connections and effective management of areas that cannot be economically served by conventional networks. What WASAC is planning The Water and Sanitation Corporation (WASAC) has outlined plans to divide Kigali into three main sewerage catchment zones: Nyarugenge, Gasabo and Kicukiro. ALSO READ: Gasabo to get dedicated sewage system The Gasabo system would serve areas draining towards Karuruma, while the Kicukiro network would cover areas including the industrial park, Masaka and Gikondo, which drain towards the Kanombe and Masaka wetlands. In early 2026, WASAC launched a tender to recruit a firm to undertake a feasibility study for a dedicated sewerage system in Gasabo. The proposed network could become Kigali’s second-largest after the Nyarugenge system. However, the study and detailed design for Phase II of the centralised sewerage project, covering Gasabo, have been suspended pending completion of Phase I in Nyarugenge. A 2022 study published in the International Journal of Scientific and Research Publications estimated that Kigali generated approximately 3,240 cubic metres of wastewater daily, with about half discharged untreated into the environment. ALSO READ: Construction of Kigali waste treatment plant at 70% For urban planners, the immediate challenge is ensuring that Kigali’s expanding sewerage infrastructure reaches more households while providing effective wastewater treatment for communities beyond the reach of conventional networks.
