The rising water demand, coupled with mismanagement and misallocation of water, has caused water scarcity in the Sindh Province of Pakistan. The Sindh province almost entirely relies on the Indus River supply to meet its agricultural demand. The rising population will demand more food, but at the same time, agriculture water share will be under pressure due to the increasing demand of other competing users. Many studies have predicted a shortfall of water in the coming years, which will cause food security issues in the country. Since agriculture is the largest water user among all sectors, effective water management in this sector will have the most significant impact. A water balance study is presented in this paper to evaluate the current and future water supply and demands and develop sustainable agriculture water budgeting. Actual evapotranspiration (ET) or consumptive water in the entire irrigated region of Sindh comprising 14 canal command areas (CCAs) during the Rabi and Kharif seasons of 2017-2019 was studied. The study utilized Landsat satellite data product from the Earth Engine Evapotranspiration Flux (EEflux). Study results identified shortages during the Rabi seasons when flows are usually low, but consumptive water use is more than the available quantum from canal flows and rainwater. However, the Kharif season presented an opposite trend. Within CCAs, the supplies and demands showed variable trends that can be balanced by adjusting surplus and deficit supplies by recalculating canal allocations. Suggestions for balancing water in these CCAs were also presented in this study.