Today I made the mistake of pouring caustic soda down a kitchen waste-pipe to unblock it. Despite reading that it's safe on plastic pipes, it created a terrible leak between the pipe and the underside of the sink. I assume it ate right through the rubber gasket.
Is this to be expected, or does it sound like the sink was badly fitted? I know how corrosive caustic soda is, but it seems like it's pretty common for exactly this purpose.