Global school closures in response to the COVID-19 pandemic affect up to 1.6 billion children and present an unprecedented risk to their education and wellbeing. WHO and UNICEF guidelines on infection prevention in schools identify a range of measures that need to be in place for schools to reopen and operate safely, including regular handwashing with soap and water, daily disinfection and basic drinking water and sanitation services. Yet the latest global estimates found that in the 60 countries identified as having the highest risk of health and humanitarian crisis due to COVID-19, one in two schools lacked basic water and sanitation services and three in four lacked basic handwashing services at the start of the pandemic. Accelerating progress in countries with the lowest coverage of WASH in schools will therefore be critical to improving school safety during the COVID-19 pandemic and beyond.