Sustainable Water, Sanitation, and Hygiene Behavior Change in South Asia: A Systematic Review

ABSTRACT The sustainability of community‐based water, sanitation, and hygiene (WASH) interventions is essential for achieving sustainable global public health outcomes. This systematic review synthesizes evidence from WASH‐related studies across South Asia (Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, Sri Lanka) on factors affecting intervention sustainability, including facilitators, barriers, and contextual effectiveness. A comprehensive search of PubMed, Scopus, and Google Scholar was conducted for English‐language studies published between 2014 and 2024. From an initial 22,933 records, 75 studies met the inclusion criteria, which focused on community‐based WASH interventions in South Asian countries. Institution‐based and emergency WASH programs were excluded. This review employed the Saunders and colleagues' process evaluation framework to examine implementation factors affecting WASH intervention sustainability. The findings indicate that interventions combining infrastructure and behavior change had more sustainable outcomes in the form of maintained behavioral changes, continued infrastructure functionality, and persistent health improvements beyond the intervention period. Interventions based on existing models and frameworks generally had better outcomes but require adaptation to contexts. Well‐monitored interventions (those with regular feedback loops) achieved higher fidelity (implementing the program as intended). However, many studies seemed to lack a sustainability‐focused design, leading to a decline in desired sustainable outcomes. Also, bottom‐up community engagement was absent in a majority of the studies despite claims of high engagement. The persistent challenges include cultural resistance, limited resources, limited equity, and inadequate local capacity. Success factors include community ownership, participatory monitoring, and alignment with government programs. These insights highlight the need for context‐sensitive, community‐driven, multi‐component strategies to achieve lasting behavioral change toward Sustainable Development Goal (SDG) 6.