The most common structures within a sewage system are sewer manholes. While they are generally small construction elements, their large quantity makes them a crucial part of the sewage infrastructure. Therefore, they form an extremely important part of the sewage system. The aim of this thesis is to describe the functions, basic components, and important factors involved in designing sewer manholes, with reference to the issues of valid literature and guidelines in relation to my experience in designing sewage system. The focus is on the sanitary sewer system. The thesis describes the requested quality requirements of the manholes, the method of taking over the works, the calculation of the works, and the method of testing the watertightness. Also, manholes were compared in terms of the very advantages of individual materials, the impact of buoyancy, an analysis of the costs and time required for the installation or construction of the manholes, and an overview of the durability of the manhole itself was given. Professional literature, valid rules and laws, standards, catalogues were used, and many years of experience in designing drainage systems. The selection of inspection manholes for the sewage system is extremely important because, together with the pipes, they form an integral part of the system. It is crucial when choosing the type and material of the inspection manhole, as well as the method of installation, to approach it systematically in the design phase, so that the construction itself is simple and fast, and ensures the reliable achievement of the designed characteristics of the system, while meeting all the required standards.