Realise, in high rise buildings suction pressure inside the drainage stack will continuously pull the traps (that means suck the water of the U traps leaving an empty and open U trap) if no vent pipe is provided, and creating COVID19 path into your home. The vent pipe is designed to prevent suction pressure (negative pressure) inside the drainage stack.
Filling each U trap once a week is not going to help if the stack in your building does not have a vent pipe (sometimes called balanced pipe) to relieve the pressure and prevent suction pulling the traps.
You don’t know what you don’t know, so go ask somebody who does :)
#drainage #design #Utrap #hongkong #drytrap