To get to the bottom of Charlie Jones’ question, it is necessary to consult the Strata Plan to determine the extent of lot property. It is not unusual for courtyard spaces to extend say 2 metres below the surface, and include airspace say 3 metres above the surface.
Having determined whether the pipe is located in common property or lot property, the definition of “common property infrastructure” in the Strata Schemes Development Act 2015 becomes relevant.
It is quite possible this is a lot owner responsibility, if it is a pipe located within lot property servicing only that property.
Even if this is found to be an issue involving common property, the cause of the blockage and damage may be relevant if the scheme has a by-law requiring owners to indemnify the owners corporation in respect of damage caused by owners to the common property. For example, the owner or tenant may have put unsuitable items down the toilet, planted a tree with aggressive roots or brought in compacting equipment to lay pavers.
A plumber who has been engaged by “Strata” will turn to “Strata” for payment.