The sewerage system is a vital component of all wastewater disposal structures. The architecture of buried municipal networks differs significantly depending on the considered city, local subsurface conditions and terrain configuration. History and characterization of sewerage system in Wroclaw which is gravitational with pressure elements (pumping stations, pressure sewers) has been presented. The total length of gravitational sewers equals to ca. 1700 km, including 1300 km combined and separate sanitary sewers as well as 400 km storm water sewers under administration of Wroclaw Municipal Water and Sewerage Systems Company only since 2010. The data about amount of wastewater and recorded failures of gravitational sewers in 2006-2008 have been collated and analyzed. The amount of wastes gathering by combined and separate sanitary sewers was equal to 43-47 million m3per year, and the average indicator of sewage effluent recalculated per one citizen of Wroclaw agglomeration equaled ca. 0.178 m3 per one day. On average per one month, the number of sewers' damages was in the range 7.3-8.3, and the average failure rate per one year and one kilometer of network length (without storm water sewers) equaled 0.07.