In double storey houses, sometimes we find that the roof of the ground floor toilet is leaking, due to the toilet on the 1st floor just above it. Due to this, the walls of the adjoining rooms are getting damped and patches of dampness tarnishing the colours of the wall. In this type of case, maximum chances of such occurrence is due to bad workmanship. There are two reasons which can cause leakage of the toilet roof.
Firstly, the leakage may be caused due to improper joints between soil pipes and the accessories. During construction, soil pipes are not properly jointed with its accessories, due to which waste water leaks through the joints. To stop leakage follow the route of soil pipe and identify the joint which is leaking and rectify it.
In second case, which is the most common case, the porcelain P or S traps gets cracked either during construction or during use. During construction, the traps get cracked due to mishandling, which is overlooked by the mason during the work and the same is fitted. In other cases, when the waste matter does not pass through the soil pipe properly and the waste gets accumulated in the water closet, we try to clean the trap with a wooden stick or an iron rod and during this process the trap gets cracked. So when you find that the soil pipe joints are proper but still the roof is leaking, give a minute observation to the traps. If you find that the porcelain P or S traps are cracked, replace them immediately with the new ones.