RTNQ – I assume that you’re an Owner, that by “our responsibility” you mean the Owners Corporation’s responsibility, and that by “managing agent” you mean the Strata Manager engaged by and working for the Owners Corporation (O/C).
As the O/C’s relationship is with its Owners, and the Owners’ relationship is with their tenants, Luke’s advice (post #2) is absolutely correct and IF the Owner/Landlord is certain that it’s their current tenant that damaged the waste pipe, then it’s up to that Owner to recover their costs from that tenant just as they would if there was damage inside their Residence.
As it appears that this waste pipe is in a position that makes it liable to damage by vehicle/s, then the O/C should at its cost place a suitable protective barrier around it to prevent future damage.
Can the O/C demand that the Owner pays?
YES – remembering of course that whilst your Strata Manager is paid by the O/C to provide it with advice in the management of its Strata Scheme, in matters such as this they must act in accordance with the O/C’s instructions.
So the O/C (Secretary) should instruct the Strata Manager to obtain quote/s to have the waste pipe repaired, to send a copy of the preferred quote to the Owner, to engage the Contractor / Plumber to do the repairs and to install a suitable barrier, to pay the Contractor from the O/C’s funds, and to invoice the Owner for a reimbursement of the repair costs ONLY.