my wall is having stain of water leakage i could only suspect it is from the basin of my bathroom next to it.  But the leakage stain may not look like it is from the basin?
And the leak is not always there when only bathing the leak will be there meaning that the source of leak is coming from bathroom or sink waste water and not from water tank.  Leakage connected to water tank will surely result in constant leak.
Here is my bathroom and my room wall next to it
Can any sifu tell me where is the leak?  Or I need to hack only can know?