Women have played important roles in the provision, management, and pursuit of knowledge about water resources from antiquity to the present. Taking a broad perspective, this commentary begins with evidence of women's water knowledge in ancient societies, including a vignette of the famous Hellenistic scholar Hypatia of Alexandria who is widely known among modern feminist scholars. It then surveys the work of women pioneers and popularizers with an emphasis on the 19th and 20th centuries. These pioneers were historical exceptions who confronted institutional and societal exclusion of women from scientific disciplines and organizations. Before concluding this historical perspective, we reflect upon the importance of women's traditional and Indigenous water knowledge, which have enormous cultural depth and geographic breadth. These historical, pioneering, and traditional bodies of water expertise pave the way and provide the context for our survey of women's contributions to disciplines of hydrology in the late 20th and early 21st centuries. To assess what has, and has not yet, been achieved, the final section presents a review of major water journals to assess their coverage of “women” and “hydrology,” and women's representation in journal editorship. The results show that while research on these topics is limited in hydrology journals as compared to multidisciplinary water resources journals, women are emerging in the 21st century with a greater proportion of leadership roles in hydrologic societies, journals, and laboratories. As women's contemporary roles in hydrologic research grow, new questions are being asked about gender dynamics in access to, and support within, the discipline.