For Save the Children (SC) this is unacceptable. In humanitarian contexts children must have access to safe water and clean toilets, enabling them to practice proper hygiene at home, in schools and in health and nutrition centres. As such, SC will strive to improve WASH interventions across our Education, Health, Nutrition, and Child Protection interventions to the reach the most deprived and marginalised children in most at-risk communities, namely those with high malnutrition rates and high rates of WASH-related diseases. Since its relatively recent creation in 2010, the SC Humanitarian WASH team has steadily increased its integrated support to other SC sectors’ outcomes. In 2017-2018 SC implemented 168 humanitarian WASH interventions across 30 countries. These interventions reached 8 million beneficiaries for an overall global humanitarian WASH portfolio of roughly $80m USD, as cited in Figures 1 and 2. Although WASH remains a subtheme in SC this rapid growth has made this guidance necessary to further clarify the position and ensure alignment of Humanitarian WASH within different humanitarian workstreams and strategies, including “Public Health on the Frontline”; the “Areas of Focus of Humanitarian Strategy Group”; the “Centenary Commitments”; the “2019-2021 Save the Children Strategic Objectives”; as well as for the “2030 Ambition Breakthroughs”. This guidance has undergone wide consultation with SC humanitarian colleagues to capture lessons learned from WASH and non-WASH programs. The purpose of this document is to provide direction to the movement on what type of WASH interventions should be applied and integrated in multi-sectoral humanitarian programs. This paper starts by outlining key WASH interventions across SC’s three pillars: Survive, Learn and Be Protected. This is followed by guidance on key cross-cutting models and approaches. Within each section there is a brief presentation of key points that will be focused on from 2019-2021 although these are not exhaustive, but rather provide an overview of important steps in moving forward in SC humanitarian WASH work.