A key challenge for humanity over the coming decades will be to meet the energy, land, water and material needs of up to nine billion people, while keeping climate change, biodiversity loss and health threats within acceptable limits. The International Resource Panel (IRP) is examining ways of achieving decoupling of economic growth from resource use and environmental degradation by improving water productivity and measurement frameworks. This report covers the analytical methods and policy frameworks needed to ensure that water use can be properly quantified over its life cycle and integrated into decoupling measures within the green economy. The paper examines methodologies for quantifying water use and environmental impacts, their underlying assumptions and the context in which they can be effectively used. The paper finds that:

water registers provide a key to the fair distribution of access to water;
accounting can provide governments with knowledge of how water is linked to the economy and human wellbeing;
water footprint assessment can provide a tool for awareness raising to highlight water issues in production and consumption;
life cycle assessment and its standards can provide benchmarking for industries;
water stewardship can help improve quantification in corporate water monitoring.

The report makes the following observations and recommendations:

water ecosystems must function properly and make clean and sufficient water available to ensure food production, drinking water supply, energy and cultural values;
effective and targeted assessments depend on open data access and optimal data availability to function in a transparent and equitable dialogue of relevant stakeholders;
the methodologies applied to the assessment of resource use and allocation need to be transparent and comparable between regions;
further efforts are needed to provide this comparability between different accounting methodologies and life cycle and footprint assessments.

The report concludes that there is a need to evaluate water resource use and management against ecosystem resilience and the limits of sustainability when developing policy options to respond to the competing needs of different water users.