Around the world, more than 2 billion people lack access to safely managed water, sanitation and hygiene services, with conflicts and climate change exacerbating the issue. Unsafe and insufficient WASH facilities, especially in rural and remote areas, can lead to increased health complications for older people, persons with disabilities and children. They also reinforce cycles of poverty, inequality and deprivation – particularly for women, children and marginalized groups, who are disproportionately impacted by a lack of equitable access to water and sanitation. Launched on World Water Day, the guidelines address the knowledge gap on ways to practically implement inclusive approaches to WASH infrastructure development, particularly in developing countries and fragile contexts.