Recent flooding in the Sydney Basin pushed thousands from their homes and left others facing enormous insurance costs. These events show how traumatic and costly it can be to live in areas vulnerable to disaster. Too often, socio-economically disadvantaged populations are disproportionately affected. Some flood dangers, however, can be far less visible – to planners, developers and home-buyers. Sometimes, the danger comes from groundwater beneath the surface. Earlier this year, for example, residents of the New South Wales town of Stuarts Point were evacuated and decontaminated after sewage spilled into their streets, as septic tanks filled with shallow groundwater. These problems are not inevitable. Our recent report shows how changes to urban planning, building design and construction practices could reduce groundwater risks. That means better outcomes for residents, developers, governments and the environment.