BACKGROUND: Research suggests that the lived experience of inadequate sanitation may contribute to poor health outcomes above and beyond pathogen exposure, particularly among women. The goal of this research was to understand women's lived experiences of sanitation by documenting their urination-related, defecation-related and menstruation-related concerns, to use findings to develop a definition of sanitation insecurity among women in low-income settings and to develop a conceptual model to explain the factors that contribute to their experiences, including potential behavioural and health consequences. METHODS: We conducted 69 Free-List Interviews and eight focus group discussions in a rural population in Odisha, India to identify women's sanitation concerns and to build an understanding of sanitation insecurity. FINDINGS: We found that women at different life stages in rural Odisha, India have a multitude of unaddressed urination, defecation and menstruation concerns. Concerns fell into four domains: the sociocultural context, the physical environment, the social environment and personal constraints. These varied by season, time of day, life stage and toilet ownership, and were linked with an array of adaptations (ie, suppression, withholding food and water) and consequences (ie, scolding, shame, fear). Our derived definition and conceptual model of sanitation insecurity reflect these four domains. DISCUSSION: To sincerely address women's sanitation needs, our findings indicate that more is needed than facilities that change the physical environment alone. Efforts to enable urinating, defecating and managing menstruation independently, comfortably, safely, hygienically, privately, healthily, with dignity and as needed require transformative approaches that also address the gendered, sociocultural and social environments that impact women despite facility access. This research lays the groundwork for future sanitation studies to validate or refine the proposed definition and to assess women's sanitation insecurity, even among those who have latrines, to determine what may be needed to improve women's sanitation circumstances.