Existing methods and techniques for calculation of hydrological characteristics of drainage systems are based on existing standards in which such parameters as climate, soils, structures and drainage system features, the data of hydrological and hydrogeological observations are not sufficiently taken into account. The article presents a method of estimating the design characteristics of the drainage from residential and industrial areas of North-West Russia, intended to substantiate structures and parameters of drainage systems, to account the volume of waste water and to determine maximum allowable discharge of water into diversion chamber. The method is based on a synthesis of available materials, with use of simple and appropriate calculated dependences of the drainage outflow characteristics on determining factors. Various factors of the soils hydrological regime are taken into account (climate, type of water supply, drainage structures and parameters of the network). The infiltration inflow and drainage flow for the north-western area of Russia are calculated.