AbstractDaily carrying of heavy loads of domestic water, especially during pregnancy and postpartum, bears a threat to maternal health in low‐income countries. Using an extended health action process approach (HAPA), we examined women's reasons for and psychosocial determinants of safe water‐carrying during pregnancy and postpartum. In a mixed‐methods study, trained local interviewers conducted 1001 quantitative interviews with women of reproductive age (n = 921 analyzed) and 21 qualitative interviews with women of reproductive age, in‐laws, and spouses in rural Nepal. We analyzed the quantitative data with generalized estimating equations to model the HAPA‐based psychosocial determinants of avoiding water‐carrying during pregnancy and postpartum. Subjective perspectives were investigated with thematic analysis. Outcome expectancies (B = 0.24), self‐efficacy (B = 0.20), and injunctive norms (B = 0.23) were significantly associated with the intention to avoid water‐carrying. Self‐efficacy (B = 0.36) and instrumental support (B = 0.05) are related to behavior (all p < 0.05). Women explained water‐carrying during pregnancy by a lack of family support, a shift of health decision‐making power to in‐laws, and low behavioral control. Overall, the necessity of water, family decision‐making structures, and low support make it difficult for women to discontinue water‐carrying. Additionally to infrastructural improvements, behavioral interventions may increase women's self‐efficacy for safe water‐carrying (e.g. reducing weight) and social support.