Despite proven impact on health, dignity and wellbeing, the field has suffered from chronic underinvestment. Because hygiene challenges are most visible in low- and middle-income countries, they are often seen as localised rather than global priorities. Yet hygiene is a universal determinant of health – one that cuts across infectious disease control, education, gender and climate resilience. Its cross-disciplinary nature means it frequently falls between funding silos with no single sector or institution owning the agenda. As a result, it lacks the sustained attention and dedicated investment required to deliver its full potential.