The estimation of water distribution system capacity, applicable in spatial planning process as an expert basis, is developed in this master thesis. The estimation has been developed for the areas of vacant building land in the City Municipality of Kranj, where certain activities are planned. In the process of spatial plans preparation such estimations are currently not made; however, they represent an important basis for new settlement areas planning, activities allocation, time definition and cost of implementing planned arrangements.
For vacant building land, where construction is possible and permissible, the estimation of average drinking water consumption was made, according to the multiannual measured existing drinking water consumption from comparable areas. The comparison was defined by the detailed land use, urban indicators and activity. Areas of vacant building land with estimation of drinking water consumption were added to the hydraulic model of water distribution system Kranj, where pressure and flow circumstances in the water distribution system were checked. We identified the necessary investments in the water distribution system and estimated the costs of it, in the case of realisation of planned arrangements on vacant building land by interpreting the results of hydraulic modelling and additional calculations of required secondary water supply network length. The results of the methodology developed proved to be useful for assessing the suitability of the existing water distribution system capacities and for planning new ones, which represents the missing basis in the process of preparation and acceptance of spatial plans.