This brief’s based on the WASH evidence gap map: 2018 update by Hugh Waddington, Hannah
Chirgwin, Duae Zehra, John Eyers and Sandy Cairncross. The 2018 update was funded by the WSSCC. The authors systematically searched for published and unpublished studies since the original 2014 WASH evidence gap map was produced and conducted new searches of behavioural outcomes and WASH provision in health facilities.
The 2018 update includes 234 additional studies in L&MICs; overall, 320 are controlled impact evaluations, 42 are systematic reviews, 47 are impact evaluation trial registries and 1 is a systematic review protocol. The authors used machine learning to improve the efficiency of the screening, enabling savings of 90 per cent in the number of studies screened.