As a consequence of the bombings of World War II and the siege, the sewer network was damaged at 153 points in a length of 3360 m. Apart from the sewer network, the pumping stations also suffered serious damages. The central pumping station suffered the most, it was hit by 32 bombs. 

The machinery of the Óbuda pump station was completely under water. As a consequence of the bomb hits, about 24,000 m³ sludge deposited in the sewers, and the operation of the network was paralysed in a length of about 105 km. Reparation started immediately after the war.
At the pump stations, the unhindered flow of wastewater had to be ensured first, the repair and replacement of the machinery equipment could only start after that. They were completely made appropriate for operation in 1947. The Budapest Capital City Sewage Works was established in the main period of reconstruction, on April 1, 1946. In the organization of the Budapest Sewage Works, the tasks of the Network Maintenance Department is the protection of the 3000 km network. By today, this work has become almost entirely automated.
Great-Budapest was formed in 1950. The area of the city has grown to 194 km², but the sewer network of almost 1300 km only grew by 300 kilometres. In a great part of the fringe districts of Budapest, separate system sewerage was built, thus the complete sewerage of the water conduit areas can be reached quicker.

As a consequence of the huge industrialization, the previously predominantly household wastewater has become mainly of industrial nature. This meant an increased threat to the water quality of the Danube. On the basis of the wastewater treatment program meant to be realized after the turn of the millennium, new wastewater treatment plants performing complete biological treatment and a collection network leading to these had to be built.
The first plant performing biological treatment in Budapest is the South-Pest plant, built between 1955-1966. The first phase of the North-Pest Wastewater Treatment Plant was finished in 1985.  

The location of the plant meant to treat the effluents of Pesterzsébet, Kispest and Pestlőrinc was defined by the National Plan Office on December 23, 1952. Besides the investment program being reshaped several times, the construction of the plant went on continuously and it operates normally since September 14, 1966. Sludge treatment was added in 1967. 

The extension of the plant was started in the 80s: 

• in 1983, the hydraulic capacity of the treatment plant was extended by the commissioned two new parallel biological treatment lines; 
• in the middle of the decade the automated dewatering of the sludge, generated in anaerobic mesophilic digestion units started; 
• in 1986, surface aeration was replaced with the more efficient fine bubble aeration technology; 
• from 1989 biogas exploitation was started; the energy produced by gas engines ensures the operation of the air blowers of the activated sludge system; 
• in 1990, biological phosphorus-removal was achieved by upgrading the aeration unit.

The hydraulic capacity further increased in 1992, when the new pre-mechanical unit ensuring also the removal of the fat and sand content of wastewater was built.

The new owners appearing in the Budapest Sewage Works in 1997 (the French Veolia Water and the German Berlinwasser) caused a considerable quality development in the life of the South-Pest plant as well. The wastewater treatment and sludge management technologies were renewed and completed.
In 1999, through the extension and modernization of the water treatment, the plant became able to completely treat biologically 80,000 m³/day wastewater, including the two-step nitrogen and phosphorus removal as well.
In 2001, the sludge management process was renewed and extended: a new, covered gravitational densifier equipped with a deodorant equipment was built, the centrifuges serving the automated densification and dehydration of sludge were commissioned, the gas engine producing electric energy from produced biogas and the solid charge biogas sulphur removal unit were also commissioned.
The high nutrient content waste collection and processing unit was handed over in 2005, while the countrys biggest capacity, high temperature thermofile sludge digestion unit and a new bigger capacity gas engine also started operating.

Pre-mechanic treatment started in 1982, while the activated sludge biological treatment and sludge management was finished in 1986. The capacity was 140,000 m³/day. After numerous transformations, the plants safety of operation and the quality of effluent water were considerably ameliorated. The plant was renewed by FCSM in 1998. The Angyalföld main conduit was finished that year, making possible the significant increase of treated water quantity. The investments that took place between 1999-2002 increased the capacity to 200,000 m³/day. The covering and deodorant of mechanical cleaning equipment was realized.
With the help of the main conduits installed under the Danube bed, the effluents of Üröm, Budakalász, Békásmegyer, Csillaghegy and Rómaifürdő were also collected in 2007. Thus the ratio of wastewater treatment in Budapest reached 51%. 

The complete sewage of Budapest (www.bpcsatornazas.hu)