The constant rate model of the IWR-MAIN software (main code developed by the U.S. Army Corps of Engineers' Institute for Water Resources) is used to forecast the water demand in the Emirate of Umm Al-Quwain (UAE) for the next twenty years. Two different databases are used: the first provides average yearly water consumptions since 1980; while the second provides more detailed monthly water consumptions but over shorter period, since the turn of the century. Model calibration indicates that using the year 2000 and 2002 as base years for databases one and two, respectively; to predict the water demand gives the most accurate results. More than 50% increase in the current water demand will be required to satisfy water needs in Umm Al-Quwain in 2020 and double of the current demand will be needed before 2030. The decision towards building new desalination plants will be taken based on these results. (C) 2010 Elsevier B.V. All rights reserved.