The Sustainable Development Goal (SDG) 6-Ensure access to water and sanitation for all underpins and is interrelated with most other SDGs as water is a critical input to meet many of the development and environmental targets. Continuous stress on the water system in terms of quantity and quality cause complex, unwanted outcomes and trigger increased environmental stress at regional and global scales, thus creating a trade-off between human water needs and environmental sustainability. Designing policy and planning investment while considering such trade-offs can help accelerate achieving the SDG targets. Otherwise, it may lead to sub-optimal or even adverse outcomes if the set of actions is not properly pre-designed considering such inter-linkages. Therefore, a holistic and transdisciplinary approach is needed to address these complex, interrelated challenges. Science and technology are powerful agents of change to support water governance and management; and science-policy-society cooperation can harness breakthroughs in our understanding of coupled human-environment systems and the shaping of innovative pathways towards achieving a sustainable water future. Moreover, new scientific and technological research, as well as the adaptation of existing knowledge and technologies to specific local and regional contexts, are needed to further support water management and governance. The chapter summarizes the current state of SDG 6 implementation and discusses how scientific tools and assessments can help prioritize actions in SDG 6 implementation.