Abstract This article gives an overview of the global water law research and provides a contemporary understanding of water law spanning across public and private law questions of natural resources use, environmental protection, and water-related disasters. The overview is based on a systematic literature review. Using HLA Hart’s distinction, we divide the various strands of water law scholarship into two main perspectives, namely the internal and the external. From the law’s internal perspective, water law research is conducted with an intent to interpret and clarify rights and obligations in existing legal instruments, such as multilateral agreements and national statutes, and case law. Based on the literature review, vibrant themes from this perspective are water use and protection, water cooperation, human right to water, rights of nature, water security, water services, and coherence between legal instruments and institutions. From law’s external perspective, the focus of water law research is to analyse and understand how law as an instrument and societal institution facilitates and steers, but also impedes, the movement of public and private actors toward certain societal goals effectively and legitimately. Here, themes such as water law in collaborative and adaptive governance, ecosystem approach, good governance, and climate change adaptation are central.