Trunk sewer „B“, with a length of 15.92 km, leads along the left bank of the Svratka. It begins in the area of Kaštanová St. via a connection to sewer „D“. It drains wastewater from a part of Komárov, the city centre, a part of Staré Brno, Nový Lískovec, Kohoutovice, Jundrov, Žabovřesky, Komín, the area of Jiráskova čtvrt, Bystrc, Kníničky and the built-up area at the Brno lake.
Collector „C“ with its 16.78 km is the longest. It starts in Křenová St. at its discharge point to „D“. It collects wastewater from the centre of Brno (Koliště, Vlhká), and from the areas called Ponava, Královo Pole, Medlánky, Řečkovice and Lesná. It leads along the Ponávka stream up to the Kuřim pumping station where it receives wastewater from the town of Kuřim.
Trunk collector „D“ is 7.46 km long. It begins in the area of Královka through a connection to collector „E“ and then it leads along the right bank of the Svitava. It provides collection of wastewater from the district of Komárov, a part of the city centre, Zábrdovice, Černá Pole and Husovice.
Collector „E“ ranks amongst the longer with its length of 13.06 km. It conveys wastewater directly to the wastewater treatment plant. It is located on the left bank of the Svitava and drains wastewater from Brněnské Ivanovice, Černovice, the district of Slatina, Juliánov, Židenice, Maloměřice, Obřany.
The last collector „F“ – 6.24 km long begins directly at the WWTP and conveys mainly sewage from the eastern part of the city. It drains wastewater from the districts of Chrlice, Holásky, Tuřany, the districts of Brněnské Ivanovice, Slatina and Líšen where it terminates. It also receives wastewater from Šlapanice, Bedřichovice and Podolí.
The trunk collectors are extended by trunk sewers conveying e.g. sewage water from the suburban residential areas via the old built-up areas as close as possible to the WWTP. The system of main sewers is connected to the system of trunk collectors and sewers and it enables draining of wastewater from the individual sub-catchment areas. Detailed drainage of the catchment area is provided by street sewers.
Siphons, overflow chambers, vortex separators, retention tanks, pumping stations, inspection manholes and other civil structures represent integral parts of each sewer systems (sediment traps, inlets, flushing structures).
The basic sewer system in the city consists of six trunk collectors marked „A“ – „F“.
Collector „A“, with a length of 7.48 km, is situated on the right bank of the Svratka River and it drains wastewater from Přízřenice, Dolní and Horní Heršpice, Bohunice, Stary Lískovec and a district of Staré Brno called Štýřice directly to the Brno-Modřice wastewater treatment plant. It also collects wastewater from the town of Modřice.