Freshwater scarcity is a global concern and is caused by the overuse of water, exceeding the sustainable level. In Pakistan, overpopulation, climate change alleviation, and economic development influence the asset of water. For water management, development, and conservation, policymakers need to formulate the right plans and projects. For this purpose, they need to evaluate the impact of different projects and plans and evaluate considerable data and information. Different tools are being adopted for integrated water resource management. Among them, WEAP is user-friendly, reliable, and efficient, and is used widely across the globe. It will aid the policymakers to develop suitable projects and plans. This study was carried out by using WEAP, in the Lower Bari Doab Canal command area (LBDC), Punjab, Pakistan. This study sheds light on the current water allocation situation and simulated scenarios of population growth rates and economic growth to evaluate the future water demand situation. The results of the current account year (2015) show that the domestic water demand of Okara (101.51 MCM) and the agricultural water demand (1713 MCM) of Sahiwal was seen to be the maximum among the four districts. Unmet demand was found to be maximum for the districts laying in the tail end (Sahiwal and Khanewal). The results of the scenarios show that, if the current water consumption, population growth, and economic development continue, unmet demand will increase in the future, and if the population grows at a higher rate and economic development increases, it will result in higher unmet water demand in the coming years. WEAP was found to be a user-friendly and efficient model to better understand water demand.