The Indus Basin Irrigation System (IBIS) is more than a century old. Water allowances and canal water distributions responded to increasing crop water requirements in a southward direction, e.g. higher water allowance in Sindh as compared to Punjab. But within a province, the canal water supplies do not address the issue of difference in irrigation demand. The consequence is unprecedented groundwater depletion in Bari Doab and waterlogging in certain other canal commands. After the Indus Waters Treaty of 1960, gradually reduced flows and ultimate desiccation of eastern rivers have also contributed towards falling groundwater levels of adjoining aquifers. In this study, water allocations in the Water Apportionment Accord of 1991, annual average canal water diversions, and irrigation demand were compared for canal commands in Punjab. Rainfall was taken as an ultimate source of water that has a beneficial impact in integration with canal and groundwater. It is concluded that the efficiency of existing irrigation systems can be improved by adopting the concept of integrated water resources management (IWRM). Thus, to avoid waterlogging and groundwater depletion, reallocation of canal water supplies amongst the irrigation units in Punjab, in proportion to the relative irrigation water demand and cropping intensities, is recommended.