Since 2019, the Hong Kong Government has been actively upgrading around 240 public toilets across the city, with the initiative extending to commercial shopping malls as well. With a budget of HK$600 million, the aim is not only to enhance public hygiene but also to align with the “Hello Hong Kong” campaign, which seeks to revitalize the tourism industry affected by the COVID-19 pandemic. As part of this refurbishment effort, promoting Hong Kong’s image as a clean and sanitary city has become a priority, making the state of public toilets a focal point. To achieve these improvements, the adoption of technological solutions like smart toilets has become essential. Smart toilets are increasingly favored by authorities worldwide as they enhance hygiene through automation and address labor shortages in the cleaning industry by enabling cleaning-on-demand. Central to the functionality of smart toilets are various IoT sensors. Here, we explore four key reasons why sensors are so crucial for smart toilet systems.