This thesis presents two different ways of draining waste-water and rainwater for settlements Vnanje and Notranje Gorice. At the moment vacuum sewage system is being built, but for comparison I also designed gravitational sewage system. The thesis describes planning process of gravitational sewage system which is based on hydrological, geological, demographic, economical and climate features of area under consideration. Knowledge of these properties is needed for appropriate design. The thesis also includes the mutual technological comparison of the two systems. In conclusion, there is based on all influencing parameters specified and justified the optimum choice. In the annex there are also hydraulic calculations for gravitational system, which confirms the adequate design of drainage.