Belgrade's Long-Unbuilt Wastewater Treatment System

A sewer network without treatment

Belgrade stands where the Sava joins the Danube, two waterways whose routes extend well beyond Serbia. Its sanitation problem was not that the city had no sewers. It had built them for more than a century. The municipal water-and-sewerage utility dates the first modern sewer works to 1905, when street channels for sanitary wastewater were dug in several central streets.^[3] A tunnel completed in 1912 transferred wastewater from the Sava catchment toward the Danube catchment.^[3] Pumping stations, collectors and interceptors followed across the twentieth century. The result was a large system designed to remove wastewater from homes and streets, but removal and treatment did not develop at the same pace.

That distinction is central to the story. A sewer network can collect household wastewater and storm runoff, convey it through tunnels and pipes, and discharge it at a river outfall without first removing pollutants. The Western Balkans Investment Framework, a partnership involving the European Union and development-finance institutions, described Belgrade's position plainly in its project record: although the city had solid drinking-water infrastructure, wastewater flows from sewerage and stormwater were discharged to the Sava and Danube without prior treatment.^[2] The record described a system covering about 180 square kilometres, with more than 1,400 kilometres of pipeline canals, collectors, pump stations and tens of thousands of connections.^[2]

The scale makes simple claims about a single pipe or a single daily volume misleading. Different parts of a large city have different catchments, connections and outlets, while rainfall changes the amount entering combined sewers. Published project material uses different capacities for proposed facilities because they serve different areas. Rather than support a precise, citywide figure for untreated discharge, the available institutional evidence supports a narrower conclusion: a substantial municipal system had long transported wastewater and runoff to the two rivers without a comprehensive treatment stage. The same evidence does not establish the often-repeated claim that Belgrade was uniquely the only major European capital in that condition; that comparative assertion depends on undefined categories and is not necessary to document the local failure.

Projects and postponed plans

Plans to change the system have repeatedly been described in terms of separate zones. The WBIF project record listed five independent sewerage areas: Central, Banat, Batajnica, Ostruznica and Bolec.^[2] It proposed plants for each. Its Batajnica project was intended to reduce groundwater and surface-water pollution along the Danube, but the database now marks that project as cancelled.^[2] Cancellation of one financing package does not mean nothing happened elsewhere. It does show why announcements of a future plant should not be treated as proof that the city had already solved the underlying problem. A networked utility requires collection, pumping, treatment and a reliable operating arrangement; a plan for one segment cannot substitute for the completed system.

The left bank of the Danube illustrates the problem at a smaller scale. In 2019, the European Investment Bank signed finance for the Belgrade-Palilula Sewerage System.^[1] The bank said the project would serve a municipality of roughly 170,000 people that lacked both a sewer network and wastewater treatment.^[1] Its stated purpose included building sewers and a new plant so wastewater could be treated before being discharged to the Danube. The project was not merely an environmental add-on. Communities without sewers rely on other arrangements, while downstream water quality is affected by whether new collection pipes lead to a treatment works or simply create another outlet.

New agreements and an unfinished task

Construction and financing remained a continuing process rather than a completed correction. In June 2024, SUEZ and VINCI Construction Grands Projets announced a memorandum of understanding with the Serbian government to construct and operate a plant at Veliko Selo.^[4] The companies described it as Belgrade's first wastewater treatment plant and gave a proposed treatment capacity of 423,000 cubic metres a day, equivalent in their terminology to 1.5 million inhabitants.^[4] That is a project target, not evidence that the plant was operating in 2024. The announcement matters because it acknowledged the treatment gap while setting out a proposed central response intended to protect both the Sava and the Danube.

Other work continued alongside that proposal. In 2025, the European Investment Bank reported new financing for wastewater infrastructure on the left bank of the Danube in Palilula. The bank said the investment combined an EU grant, an EIB loan and a contribution from the City of Belgrade, and that residents would gain access to modern sewerage infrastructure.^[5] Its description of the expected outcome was similarly prospective: treated wastewater would be discharged into the Danube after the facility became operational. The future tense is important. It records committed investment and a direction of travel, not a retroactive finding that the older untreated discharges had ended.

Why the basin matters

The EIB project record connects improvements in Palilula to protection of the Danube and ultimately the Black Sea.^[1] That is an infrastructure objective, not a measurement of how much pollution from Belgrade reaches every downstream place. It identifies the relevant scale: a local outfall belongs to a river basin in which water quality cannot be managed within one municipality alone.

The problem was therefore a long-term infrastructure gap at the confluence of two international rivers. Belgrade's historical utility record shows sustained investment in the physical means to collect and carry wastewater. The later institutional records show the missing treatment capacity, divided projects, cancelled proposals and renewed financing intended to close that gap. Treating the issue as a single dramatic discharge obscures its administrative character: decades of urban growth and sewer construction were not matched by a citywide system for cleaning what the sewers carried. The consequences extend beyond city limits because the Sava flows into the Danube at Belgrade, and both rivers connect the capital's local public works choices to a wider basin.