Conducting process evaluations of WASH interventions: a scoping review of design approaches and indicators in low-...

Process evaluation is a key methodological approach in implementation science, used to examine how interventions are delivered, adapted, and experienced in real-world contexts. While widely applied in clinical and public health settings, its use in the water, sanitation, and hygiene (WASH) sector is less documented. This review synthesized process evaluation methods used in WASH interventions in low- and middle-income countries (LMICs) to inform more systematic, framework-guided, and actionable implementation-focused evaluations.

We systematically searched five electronic databases (Ovid MEDLINE, EMBASE, Scopus, Web of Science, and Global Health) and conducted outreach to researchers and practitioners to identify additional peer-reviewed and grey literature. Eligible studies included process evaluations or fidelity assessments of WASH interventions in LMICs, published from January 2008 onward. Data were extracted on study characteristics, use of conceptual or theoretical frameworks, methods, data types, and process indicators mapped across standard domains.

Twenty-four studies were included, spanning diverse WASH interventions. Sixteen studies used a conceptual or theoretical framework to guide process evaluation. Most (63%) used both quantitative and qualitative methods, while 29% used quantitative and 8% used qualitative methods alone. Process evaluations utilized multiple data types, including programmatic data, household surveys, qualitative interviews, focus group discussions, and structured observations. We identified 33 quantitative and 16 qualitative process indicators across 6 domains-fidelity, dose delivered, dose received (exposure), dose received (satisfaction), reach, and recruitment-to facilitate synthesis and identify patterns in how implementation was assessed. Quantitative approaches most frequently assessed fidelity, dose delivered, dose received (exposure), and reach, while qualitative approaches explored dose received (satisfaction) and recruitment.

Process evaluation is increasingly used to strengthen the design and delivery of WASH interventions, yet variation persists in how implementation is defined, measured, and reported. More intentional application of frameworks and structured reporting can enhance the clarity and comparability of implementation assessments, including more systematic approaches for describing context. By consolidating quantitative and qualitative indicators and the data types used to measure them across 6 domains, this review provides a foundation to support more transparent, standardized, and framework-guided process evaluations that can strengthen learning, adaptation, and implementation practices in the WASH sector.