As part of the design work, a sewerage system had to be designed for areas in South Buda and on Csepel Island and for connected municipalities (Érd, Diósd, Tárnok, Budaörs and Budakeszi) and approval had to be obtained for the designs. According to the basic concept, the whole area would have been implemented under a uniform ISPA/KEOP EU tender. It received support later as three independent projects. During design, sewer main networks in a total length of about 400 km and, connected to it, about 70 intermediate lift stations were designed.

In addition to the sewer main networks, sewage from the South Buda and Csepel Island catchment areas is conveyed to the Central Sewage Treatment Plant via the South Buda–Danube Crossing–Csepel Sewer Main System. About 7 km of gravity sewer main with diameters ranging between DN 500 and DN 1,200; about 6 km of pressure sewers with diameters ranging between DN 300 and DN 500; and about 6 km pressure sewer pairs with diameters of DN 2 × DN 600 were designed as components of the system. In addition, six high-performance lift stations and a 600 m long sewer section crossing the Danube belong to the system.

Pre-design works

• geodetic surveys;
• soil mechanics testing, preparation of an expert’s report;
• periodic measurement programme;
• hydraulic review;
• preparation of an all-inclusive water balance for Budapest;
• assessment of building sewer connections.

Design and approval work

• preparation of water licence designs in principle;
• conurbation reclassification study;
• preparation of water establishment approval designs.

Construction has been carried out separately, in several phases since 2011. The design area affects more than 200,000 residents in total. Under the project, full sewerage service was provided for the areas concerned.