Due to the annual shortages of drinking water, mainly in dry periods, the coastal region needs effective measures to provide the public with the necessary quantities of drinking water. The most promising among the variety of solutions is the use of an alternative source of drinking water – the desalination of seawater. Possible desalination methods with emphasis on the membrane process reverse osmosis are described in the first part of the thesis. The second part holds the analysis of water consumption in the coastal region within the ten year period from 2006 to 2016. Furthermore, three short simulations were made in order to test if the desalination plant can effectively replace at least one back-up source of drinking water in the water system of Rižanski vodovod Koper and still cover larger quantities of water consumption.