BackgroundWater and sanitation programs historically have focused on women’s instrumental value in improving effectiveness and impact of programs, though focus is shifting to consider how programming and conditions may contribute to women’s empowerment an gender equality. To date no systematic review has comprehensively assessed and synthesized evidence on water and sanitation and women and girls’ empowerment. The primary aims of this review were to: a) identify empirical water and sanitation research that engaged empowerment and/or empowerment-related domains from a pre-specified conceptual model; b) tabulate and report how empowerment-related terminology was used, where and when research was conducted, what methods were leveraged, and if water and/or sanitation was the primary focus; c) synthesize findings by empowerment domain and water and/or sanitation focus.Methods and FindingsThe conceptual model of women’s and girls’ empowerment developed by van Eerdewijk et.al (2017) informed our search strategy and analysis. The model presents three interrelated domains (agency, resources, institutional structures) and 13 sub-domains of empowerment. We searched MEDLINE, EMBASE, CABI Global Health, PsycINFO, CINAHL and AGRICOLA for any peer-reviewed sources presenting research related to water and/or sanitation and either empowerment and/or related terms from the conceptual model (4 May 2020). Systematic and ancestry and decendency searching identified 12,616 publications, of which 257 were included following screening, representing 1,600,348 participants. We assessed all studies using the Mixed-Method Appraisal Tool (MMAT). We followed the ‘best-fit framework synthesis’ approach for analysis, using the domains and sub-domains of the conceptual model as codes to assess all included sources. During coding, we inductively identified two additional sub-domains relevant to water and sanitation: privacy and freedom of movement. Thematic analysis guided synthesis of coded text by domain and sub-domain. The majority of research took place in Asia (46%; 117) or Africa (40%; 102), engaged adults (69%; 177), and were published since 2010; (82%; 211). A greater proportion of studies focused on water (45%; 115) than sanitation (22%; 57) or both (33%; 85). Over half of articles use the term empowerment yet only 7% (17) provided a clear definition or conceptualization. Agency was the least commonly engaged domain (47%; 122) while the Resources domain was dominant (94%; 241). Measures for assessing empowerment and related domains is limited. This review was limited by only including sources in English and only includes menstruation-focused research in the context of water and sanitation.ConclusionsWater and sanitation research specifically engaging women’s and girls’ empowerment in a well-defined or conceptualized manner is limited. A substantial body of research examining domains and sub-domains of empowerment exists, as does research that illuminates myriad negative impacts of water and sanitation conditions and circumstances women’s and girl’s well-being. Available research should be used to develop and evaluate programs focused on improving the life outcomes of women and girls, which has only been minimally conducted to date. A more comprehensive ‘transformative WASH’ that includes gender-transformative approaches to challenge and reduce systemic constraints on women’s and girls’ resources and agency is not only warranted but long overdue.