The problem of water sanitation and hygiene gaps persisting continues to affect hundreds of millions of people and undermines progress on multiple Sustainable Development Goals. Existing responses remain fragmented, under-resourced and poorly adapted to local contexts. A strong solution must operate effectively under severe constraints of skilled personnel, infrastructure, electricity and connectivity. It should define clear measurable outcomes, identify possible unintended harms, and demonstrate how the intervention can be sustained by local institutions long after initial funding ends.