The article describes an introduction to the problem of drainage of flat roofs, namely by using a vacuum drainage system. The article describes the current state, which also describes the gravity drainage system, whose design is in partial "retreat", unless required by local conditions or the investor of the construction. The following describes the advantages and disadvantages of the vacuum system and some design principles. The fourth chapter deals with the most common problems of the system, which include hydraulic system alignment, where the correct design of the system is carried out by hydraulic calculation of the system branches, using special software. The vacuum system must be designed in the correct dimensions, with suitable outlets and in such a way that it is not adversely affected by eg obstacles on the roof. Other mentioned problems include the level of noise and vibration of the system, which arises especially at higher intensity of rainfall, which leads to fluctuations between gravity and vacuum mode of water flow in the pipeline. These problems will be solved in the following research activity. Laboratory testing of hydraulic quantities and other parameters will be performed on a test equipment. The measured results will be further evaluated.