TL;DR
- The answer depends on one thing: whether the leaking pipe is common property or lot property. That classification is set by the strata plan, not by which apartment the water appears in.
- Pipes inside boundary walls, floors, or ceilings between two apartments are almost always common property. The owners corporation is legally required to arrange and pay for the repair.
- Pipes that serve only one lot and sit entirely within that lot’s boundary are the lot owner’s responsibility.
- If it’s not clear which category applies, get the source found first — then the responsibility question usually answers itself.
- The two-year clock matters: if you’ve suffered loss from a common property leak, you have two years from the date you became aware to claim reimbursement from the owners corporation.
Why this question is harder than it looks
A pipe is leaking somewhere between two apartments. Water is appearing in the ceiling of the unit below, or tracking through a shared wall. Nobody can see the pipe. Nobody is sure whose it is. And both residents want the problem fixed before more damage builds up.
The instinct is to point fingers — at the neighbour above, at strata, at whoever moved in last. But the actual answer in NSW comes from the law, not from proximity to the leak. Specifically, it comes from the Strata Schemes Management Act 2015 and the registered strata plan for your building.
Here’s how to work through it.
Step 1: Understand what the law actually says
Under Section 106 of the Strata Schemes Management Act 2015 (NSW), the owners corporation has a strict legal duty to maintain and repair common property. Strict means exactly that — the obligation applies regardless of how the fault occurred, how old the building is, or whether the problem was caused by original construction. If it’s common property, the owners corporation arranges the repair.
Lot owners, on the other hand, are responsible for fixtures, fittings, and pipes that sit entirely within their own lot boundary and serve only their lot.
The critical question is always: which side of that boundary does the leaking pipe sit on?
Step 2: Work out whether the pipe is common property or lot property
This is where most disputes get stuck. The boundary between common property and lot property in a NSW strata scheme is defined by the registered strata plan — not by what feels fair, and not by which apartment the water is dripping into.
As a general rule under NSW strata legislation, the lot boundary runs along the inner surface of floors, ceilings, and walls. The structural fabric of those surfaces — the slab, the boundary wall itself — sits outside the lot. That means pipes running inside boundary walls, floors, or ceilings between two apartments are typically common property, regardless of which apartment they notionally “belong to”.
There’s also a second rule that catches people off guard: any pipe that serves more than one lot is common property, even if it physically passes through your apartment. The location of the pipe matters less than what it serves.
A quick way to place a concealed pipe:
- Pipe in a boundary wall, floor slab, or ceiling between two apartments: almost certainly common property — owners corporation arranges the repair.
- Pipe serving more than one lot (shared riser, common drain stack): common property — owners corporation arranges the repair.
- Pipe inside a non-boundary internal wall, serving only your unit: lot property — the individual lot owner arranges the repair.
- Pipe from a fixture (tap, dishwasher, flexible hose) inside the unit boundary: lot property — the individual lot owner arranges the repair.
Step 3: Find the source before arguing about responsibility
The single most useful thing anyone can do when a concealed pipe is leaking between two apartments is get the source properly located. Not guessed at. Not assumed from where the water appears. Actually found.
Water travels. A leak in a pipe inside the floor slab can track sideways several metres before it shows up on a ceiling below. The stain on your ceiling is not a reliable map to the pipe above it.
A licensed plumber with leak detection equipment — acoustic listening devices, thermal imaging, or a pipe camera — can pinpoint the source without opening every wall in the building. Once the exact location is confirmed, the common property or lot property question usually resolves itself. If the pipe is in the slab between floors, it’s common property. If it’s inside a flexible hose under a kitchen sink, it’s the lot owner’s problem.
If you’re not sure what leak detection actually involves, the post on how plumbers find hidden water leaks covers the methods in plain terms.
Step 4: Notify the right people in writing — straight away
Whether you’re the resident with water coming through the ceiling or the resident above who suspects a pipe in their bathroom is the source, the first practical step is the same: notify the owners corporation or strata manager in writing, and do it today.
There are two reasons this matters.
First, the owners corporation cannot arrange a repair it doesn’t know about. A phone call to a neighbour is not a formal notification. An email or written notice to the strata manager is.
Second, there’s a two-year time limit. Under Section 106(6) of the Strata Schemes Management Act 2015, a lot owner cannot claim reimbursement for loss caused by a common property failure more than two years after they first became aware of that loss. The clock starts from when you knew about it — not from when the repair eventually happens.
What the owners corporation is required to do
Once notified, the owners corporation has a legal obligation to act. This isn’t discretionary. The duty under Section 106 is strict — the owners corporation must maintain and repair common property, and a concealed pipe leak between apartments that originates from common property falls squarely within that obligation.
In practice, this means the owners corporation (or strata manager acting on its behalf) should:
- Arrange for a licensed plumber to locate the source of the leak.
- Confirm whether the pipe is common property or lot property.
- Commission and pay for the repair if the pipe is common property.
- Coordinate access to both apartments if needed.
If the owners corporation takes no action after being notified in writing, the affected lot owner can request a motion at the next strata committee meeting, or apply to NSW Fair Trading for mediation to move things along.
What if the leak comes from a lot owner’s fitting — not a common pipe?
This is the scenario where responsibility shifts to an individual lot owner. A burst flexible hose under a kitchen sink, a failed tap fitting, a cracked supply line inside a bathroom wall that serves only that unit — these are lot property, and the lot owner above is responsible for arranging and paying for the repair.
That said, the owners corporation’s strata insurance policy may still cover some of the resulting damage to the building fabric, depending on the policy terms. Contents damage — furniture, flooring, personal items — is usually a separate matter for each owner’s contents insurer.
If the lot owner above won’t cooperate or disputes responsibility, the strata manager can often pursue the matter through a chargeback by-law if one exists in the scheme. Legal advice may be needed in genuinely contested cases.
For more on what to do when you’re the resident receiving water from above, the post on water leaking from the unit above covers the immediate steps in detail.
The grey area: when it’s genuinely not clear
Some buildings — particularly older Sydney apartment blocks from the 1960s and 1970s — have plumbing layouts that don’t map neatly onto the strata plan. Pipes have been rerouted. Walls have been moved. The strata plan may not clearly show where a particular pipe runs or what it serves.
In these cases, the safest approach is to get the leak located professionally before anyone makes a claim about responsibility. A CCTV drain camera or acoustic leak detection will produce a report that shows exactly where the fault is, which pipe it involves, and what that pipe serves. That report becomes the evidence base for the responsibility conversation — and it’s far more useful than two neighbours arguing over whose bathroom is wetter.
If the strata manager or owners corporation is slow to act and damage is building, a lot owner can engage a licensed plumber directly to locate the source. The cost of that investigation can be presented to the owners corporation as part of a reimbursement claim if the leak turns out to be a common property fault.
A quick reference: who arranges what
| Pipe location and function | Who arranges the repair |
|---|---|
| Pipe inside a boundary wall, floor slab, or ceiling between two apartments | Owners corporation |
| Shared riser or drain stack serving multiple lots | Owners corporation |
| Pipe serving only one lot, inside that lot’s boundary | Lot owner |
| Flexible hose or tap fitting inside a unit | Lot owner |
| Source genuinely unclear | Owners corporation should arrange diagnosis; responsibility confirmed after source is found |
What to do right now
If you’re dealing with a concealed pipe leak between apartments right now, here’s the order that makes sense:
- Photograph the damage — ceiling stains, wet walls, any visible water. Date the photos.
- Notify the strata manager in writing today — email is fine. Keep a copy.
- Don’t wait for strata to move slowly — if water is actively damaging your property, you can engage a licensed plumber to locate the source and present the cost to the owners corporation if it’s a common property fault.
- Don’t open walls yourself — concealed pipe repairs in NSW must be done by a licensed plumber. Unauthorised alterations to common property can create legal complications.
- Keep records of every loss — replacement costs, alternative accommodation if needed, damaged items. You have two years to make a claim, but you need the documentation to support it.
If you need a licensed plumber to locate the source or carry out the repair, call Jasco on the contact page or book online. We work across Sydney apartments and strata buildings, and we can provide the written report that makes the responsibility question easier to resolve.