In the midst of the COVID-19 pandemic, the demand for hygiene and sanitation has never been higher. A sample taken from the rooftop ventilating pipe of the sewage system of Heng Tai House was tested positive for the virus, which proves that virus can be travelled up through the rooftop ventilating pipe, before a slow-moving wind sent it back down to the building. Hence a customized UV sterilizing device for ventilating pipe of drainage system is designed, which could be integrated to a current ventilating pipe system for reducing the risk of spreading virus through the system. The device is placed on the vent pipe outlet and serves two main functions. The first one is to use the ultraviolet light properties to sterilize the vent pipe internal surface. The second function is to use the antibacterial sanitizing solution in the spiral section, it makes the air contact the more solution to prevent the breeding of germs. The device does not jeopardize the performance of the ventilating pipes system as prescribed in the Building Regulations and shall comply with other allied regulations. It is easy-to-install and has extended benefits to improve safety and health of the built environment.