Water is one of Earth's fundamental natural systems and is critical to sustain human existence. Water literacy is a key outcome for learners of all ages, who should understand how water interacts with both natural and human systems to engage in informed decision-making and support effective water management. This research aims to examine water-related standards for K-12 teaching and learning from an array of disciplines to develop a comprehensive and transdisciplinary perspective on water education. We ask, "What do disciplinary standards specify as outcomes for students' learning about water?" Our research questions are: i) "To what extent do water-related standards address recognized domains of learning?", and ii) "What thematic outcomes for students' learning are apparent across grades in water-related standards?". The study addresses both human and natural dimensions of water. We use chi-square statistics and a conventional qualitative content analysis complemented by processes from grounded theory to analyze water-related education standards (N=477) from 12 education-oriented, non-governmental organizations mostly based in the United States. First, standards emphasize the cognitive domain, including declarative and procedural knowledge for water-related concepts and skills. Although the affective domain and its social and emotional components are less prevalent, they are also key for students' learning to help support water management practices. Second, standards illustrate four sub-categories of natural dimensions of water, and nine sub-categories of human dimensions of water spanning K-12 grade bands. These results can help inform teaching and learning to cultivate water literacy, including curriculum development and classroom pedagogy.