This report aims to raise awareness of the challenges and opportunities associated with the use of fresh water and the reuse of water produced in oil and gas operations, with the view to support evidence-based policy making and regulation. To that end, the report proposes a list of operational and policy guidelines for the use and reuse of water in petroleum operations. It focuses on the water-hydrocarbons nexus, but most of the insights and findings are relevant to mining activities in general. This report addresses policy makers in emerging and developing economies seeking to devise policies to mitigate the impact of oil and gas operations on the environment. It also aims to help them identify what can be done to integrate climate resilience into investment and economic policies to support in-country value creation and the development of diversified sources of green growth. The report also may be useful to donor organizations, institutional investors, private foundations, and fund manager, as potential mitigation and adaptation project funders, to help them understand how finance mechanisms may be tailored to support climate-sensitive sector and industrial policies.