The most of sewerage networks in Slovakia were built in the last century. Due to the increase in the number of inhabitants in towns and hydrological changes, it is necessary to re-evaluate sewerage networks' capacity. Overloading the network's hydraulic capacity can lead to the occurrence of urban floods, which are one of the negative impact of a high degree of urbanization. The aim of the paper was to assess the hydraulic conditions of a selected sewer collector in the city of Trnava. A mathematical model of the sewer network was created, which was used to simulate two different load cases with varying properties of precipitation. SCA's load state was characterized as a starting case, as the properties of the design rain corresponded to the design rain in the standard STN EN 75 6101. The simulation showed that 51.9% of the network has satisfactory conditions, and 48.1% of the network is congested. Under rain load with a periodicity of p = 0.1, the results were as follows: 41.9% of the network comply with the assessment, and 58.1% of the network was congested.