Pakistan’s existential reliance on the Indus River Basin for water security is threatened by population growth, climate change, and increasing intersectoral demands. Pakistan’s National Water Policy of 2018 (NWP) adopts ‘More Crop per Drop’ as a key policy platform. Within the ‘More Crop per Drop’ strategy the NWP mandates banning flood irrigation nationally and introducing high efficiency irrigation systems (HEIS) to save water. The concept of water use efficiency (WUE) and the impact of replacing flood irrigation with HEIS on basin-wide water use are contested in the context of Pakistan. Research is lacking on how this aspect of the ‘More Crop per Drop’ strategy was included in the NWP and the evidence on which it is based. This paper addresses the gap in the literature by presenting the results of a Delphi study exploring the origins of the strategy, identifying the prevalent WUE paradigm in Pakistan, and exploring the level of appreciation of the effects of the strategy on the so-called rebound effect and water security. The study identifies that the NWP was developed mainly by the Water and Power Development Authority supported by provincial water management institutions, influenced by international funding agencies. The study establishes that the irrigation efficiency paradigm (IEP) is the dominant paradigm operating in the water bureaucracy. The farm-scale focus of this paradigm does not account for the basin-level rebound effect or the potential negative impact of the policy on water security. The study also finds that government extension workers are key sources of information for farmers considering the adoption of HEIS. We caution that banning flood irrigation and introducing HEIS in the absence of an appropriate regulatory framework could worsen Pakistan’s water security rather than ‘save’ irrigation water for reallocation and foreshadow additional research to further explore the situation. •Pakistan has an existential reliance on the Indus River for water security.•Pakistan’s National Water Policy requires adoption of More Crop per Drop.•Adoption of More Crop per Drop in closed basins can increase water withdrawals.•Widespread adoption of More Crop per Drop in Pakistan could threaten water security.•Reviewing Pakistan’s Water Policy may be important and timely for water security.