ABSTARCT The aim of this thesis is to treat the problem of wastewater pretreatment on the sewer network with a focus on storm water overflow and their impact on waterways with regard to The Methodological Manual for Assessment of storm water overflow within uniform sewerage systems in urban areas. This work describes the legislation relating to storm water overflow and includes comparison with other countries. Furthermore, there is processed the outline of objects and equipment which can be used for wastewater pre-treatment in the sewer network. In the practical part of the thesis there is designed a new solution for the mobile spillway edge of the storm water overflow OK2A, which is located within the sewer network in Brno. In the practical part of the paper there is depicted the project documentation of newly designed equipment and objects. Water management companies, design offices, students and the general public can use this thesis as an inspiration.