In this contribution by UNU-INWEH to Rio+20 the authors undertook an examination of the changing language of water in high-level declarations from eleven UN conferences on water and the environment over the past forty years. Both deepening and shallowing of key terms were evident throughout the documents and the report suggests effective strategies for highlighting and strengthening key concepts. The themes covered include: Water Scarcity, Water Security, Desertification, Water Quality, Sanitation, Science and Technology, Poverty, Gender, Food, Climate Change, and Health. Moreover, there is a four page ?Summary for Decision Makers? which distills the lessons learned from a synthesis of water discourse over four decades of UN Declarations. The study will facilitate the efforts of Ministers and Policy Makers to both build on and avoid unnecessary overlap with work done at previous meetings. The findings of the report should assist drafters of CSD documents ensure their outputs are effective, robust and reflect mindful and cumulative deepening of work undertaken at previous high-level meetings. The report was co-authored by UNU-INWEH Senior Fellow and Knowledge Broker, Dr. Alex Bielak, working with Dana Mount, a PhD student he is supervising as part of the joint McMaster University/UNU-INWEH graduate diploma program, Water Without Borders.