In 2003, WHO published a final report into a superspreading event of SARS within a housing block in Hong Kong.1 The 50-storey building had 342 confirmed cases of SARS and 42 deaths. The report identified defects in the wastewater plumbing system as a transmission mode within the building, which facilitated the transport of “virus laden droplets” through empty U-bends in bathrooms. This airborne transmission route was aided by bathroom extract ventilation, which drew contaminated air into the room. Since then, our research group has been investigating mechanisms of cross transmission, improvements in system design, and innovations in system monitoring, including confirmation of the wastewater plumbing system as a reservoir for pathogens.2, 3