It is the single most common thing we are called to in the unit stock across this area, and it usually arrives after several visits from somebody else. An owner reports a slow drain, someone clears it, it comes back in a few months, and a different owner pays for the next clear on the same line. Over a few years a scheme can spend more on clearing than the permanent repair would have cost.
The reason is nearly always structural: a cracked or displaced joint somewhere in a common stack or a common sewer line, with roots or fat catching on it. Clearing removes what has caught; it does not remove what is catching it. Twenty minutes with a camera tells you which of those you are dealing with, and it is the difference between a maintenance line item and a capital works decision.
Where the fault is in a section that can be relined, the repair goes in through an existing access point — no excavation through a driveway, a car park or a garden bed, and no closing the building down. That matters more in a strata building than anywhere else, because the cost of getting to a pipe in an occupied building is usually larger than the cost of the pipe.
We give you the footage either way. A committee deciding whether to spend money on a drain should be able to see what it is spending it on.