This technical note provides additional information to support water, sanitation and hygiene (WASH) interventions as part of the ongoing COVID-19 response at national and sub-national levels. The note supports both formal and informal WASH institutions (including public and private) to address the water, sanitation and hygiene needs of the most marginalized populations in informal settlements. It promotes partnerships and recognition of all relevant institutions including water and sanitation utilities, municipalities, small-scale and informal service providers as well as deliberate strategies to address the WASH needs of populations in slums and informal urban settlements.