Fresh Water scarceness is the global concern and is caused by overuse of water, exceeding the sustainable level. In Pakistan, over population, climate change alleviation, and economic development is influencing the valuable asset of water. For water management, development and conservation; the policy makers needs to formulate appropriate plans and projects. For this purpose they need to evaluate the impact of different projects and plans, and requires 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 policy makers to develop suitable projects and plans. This study was carried out by using WEAP, in Lower Bari Doab Canal Command area (LBDC), Punjab, Pakistan. This study throw 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 current account year (2015) showed that the domestic water demand of Okara (101.51MCM) and Agricultural water demand (1713 MCM) of Sahiwal was observed to be maximum among 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 showed that if the current water consumption, population growth and economic development continues, unmet demand will increase in the future and; if the population grows at higher rate and economic development increases it will results in Higher Unmet water demand in the coming years. WEAP was found to user friendly and efficient model to determine the water demand.