Water Leaks and Moisture in Strata: Whose Problem Is It?

Ask any committee member who's done a stint on a self-managed scheme which repair caused them the most grief, and the answer is almost always the same: water. Not because a leak is hard to fix — a plumber can usually do that in an afternoon — but because a leak is the one repair where the damage and the cause are in different places, often owned by different people, and everyone's first instinct is that it isn't theirs. The stain appears on the ceiling of unit 2. The water came from the bathroom of unit 5, three floors up, or from a common stormwater pipe in the wall, or from a failed waterproofing membrane on a common balcony. Until someone actually traces it, nobody knows who pays — and while they argue, the water keeps coming and the damage keeps growing. This guide is about working a leak the right way round: stopping the water, finding the source, allocating the cost to whoever the source belongs to, and getting the damage made good — in that order, because doing them out of order is how schemes end up paying twice for the same repair.

The one principle that settles most leaks: source, not symptom

If you take nothing else from this guide, take this:

Responsibility for a water leak follows its source, not the place the water shows up.

Water obeys gravity, not property boundaries. It runs down through slabs, along the top of ceilings, inside wall cavities, and pools at the lowest, weakest point — which is very often a lot that had nothing to do with causing it. The owner staring at a spreading brown stain on their ceiling is almost never the person who owns the problem. So the entire question of "whose problem is it?" collapses into a single earlier question: where is the water actually coming from? Answer that, and responsibility usually answers itself:

• The source is common property — a corroded common pipe, a shared stormwater or sewer stack, a failed waterproofing membrane on a common balcony or roof, a leaking common gutter or planter box. Then it's the owners corporation's to fix, and usually to make good the resulting damage to the affected lot.
• The source is a single lot — that lot's own bathroom waterproofing that the owner renovated, an overflowing appliance, a hose left running, a branch pipe that serves only that lot. Then it's the owner's, even though the damage landed on a neighbour.

Everything else in this guide is really about how to establish that one fact reliably, and what to do when it's genuinely shared or unclear.

Why leaks get so messy

Three things make water disputes uglier than any other repair:

• The damage is visible and the cause is hidden. The owner with the ruined ceiling can see exactly what they've lost and wants it fixed now; the source is behind a wall or under a floor and takes investigation to find. That mismatch breeds suspicion.
• The people involved are neighbours. A roof repair is the committee versus a contractor. A leak is often owner versus owner, living above and below each other, and the committee stuck in the middle. It gets personal fast.
• Delay makes it worse. Timber swells, plaster crumbles, and — the real danger — mould takes hold within days. A leak left to "sort out who's responsible first" turns a plumbing bill into a health problem and a much larger remediation.

Work it in this order

The single biggest mistake committees make is arguing about who pays before anyone has stopped the water or found the source. Reverse it. Here's the sequence that keeps a leak from spiralling.

1. Stop the water and limit the damage first

Before responsibility is settled, before quotes, before anyone's found the source — stop the flow and contain the damage. Turn off the relevant water supply, catch and clear standing water, lift or protect at-risk floor coverings and contents, and get air moving to start drying. This is genuinely urgent: every extra day wet is more damage and more mould. The cost of emergency make-safe work is small and can be sorted out in the wash-up; the cost of not doing it compounds. Most committees have authority to spend on urgent make-safe without a vote — check your scheme's spending rules, but don't let a process question hold up a bucket and a wet-vac.

2. Investigate the source — this is the whole game

You cannot allocate a leak you haven't traced. Get a professional to find the source: usually a plumber, and for anything structural or ambiguous a leak-detection specialist or building consultant with moisture meters, thermal imaging, or dye/flood testing. This costs money and someone has to front it — but it's the cheapest money you'll spend on the whole job, because it's the step that tells you who owns everything after it.

Who pays for the investigation? Practically, one of three ways: the owners corporation fronts it (common where the source is likely common property or crosses lots), the affected owner fronts it and is reimbursed if the source turns out to be common property, or it's split until the source is known. What matters is that someone commissions it quickly rather than waiting for agreement on who pays — write down that the cost is provisional and will be reallocated once the source is found.

3. Allocate responsibility to the source

Now — and only now — apply the source-not-symptom rule. Once the plumber or consultant has identified where the water originates, match it to the property boundary and the services rule (a pipe or component serving one lot is generally that lot's; one serving multiple lots or the common property is the scheme's — see Common Property vs Lot Property for how that boundary is drawn). That tells you who fixes the source.

4. Fix the source, then make good the damage

Two separate jobs, often two separate parties. Fixing the source (re-membrane the balcony, replace the pipe, re-seal the shower) belongs to whoever owns the source. Making good the damage — the ruined ceiling, the stained walls, the warped floor in the lot below — usually follows the same responsibility, but this is where insurance comes in (below). Never make good the damage before the source is fixed: repaint the downstairs ceiling while the balcony above is still leaking and you'll be repainting it again next month. Find and fix the cause first; cosmetic make-good is always last.

Where strata leaks actually come from

Most schemes see the same handful of sources over and over. Knowing the usual suspects helps you brief the plumber and set expectations about who's likely responsible.

• Bathroom and wet-area waterproofing. The membrane under a shower or bathroom floor fails, and water tracks into the wall or the lot below. Responsibility is genuinely contested here — the structural slab and original waterproofing membrane are commonly the owners corporation's, but where an owner has renovated the bathroom and the new waterproofing failed, it's usually theirs. Whether the original membrane was ever common property varies by scheme and plan — treat wet-area leaks as needing specific investigation, not assumption.
• Balcony and terrace membranes. A common flashpoint. The waterproofing on a common-property balcony slab is typically the scheme's; the tiles or surface an owner may be responsible for. Water off a failed balcony membrane very often lands in the lot directly below.
• Common pipes and stacks. Shared stormwater, sewer, and water-supply pipes running through the building are common property. A corroded or blocked common stack is the scheme's — and one of the clearer allocations.
• Single-lot branch pipes. The line that serves only one lot is generally that owner's, even where it runs through a common wall or floor to get there. A leaking flexi-hose under one unit's sink is that owner's problem, wherever the water ends up.
• Roof, gutters, box gutters, and downpipes. Almost always common property. Blocked box gutters and failed roof flashings are a frequent source of top-floor leaks.
• Planter boxes and podium gardens. Notorious. Common-property planters with failed waterproofing leak into the structure and the lots beneath — expensive and often argued.
• Windows and external walls. Water driving in through a failed window seal or a cracked external wall usually traces to common-property structure — but check your by-laws, since some schemes hand window maintenance to owners.

Condensation and rising damp are not always a leak

Not every wet wall or musty smell is a plumbing leak, and getting this wrong wastes money chasing a pipe that isn't broken. Condensation — from poor ventilation, drying washing indoors, or a bathroom without an exhaust fan — produces damp, mould-prone surfaces with no burst pipe behind them, and the fix is ventilation and behaviour, often the occupant's to manage. Rising damp and penetrating damp through below-ground or external walls are building-fabric problems, usually common property. A good moisture investigation distinguishes these from an active leak; if the "leak" only appears after a hot shower or in a closed-up room, suspect condensation before you rip open a wall.

Insurance: where it fits, and where it doesn't

Strata insurance changes the picture, and committees frequently forget to bring it in.

• The building policy (which every strata scheme must carry) generally covers damage to the building — including the fabric of lots — from an insured event, and a sudden escape of water is usually one. So the make-good of a water-damaged ceiling or wall may be an insurance claim, not a levy expense, subject to the policy excess.
• What insurance typically won't cover: the cost of fixing the source itself (repairing the failed pipe or membrane is a maintenance cost, not damage), gradual deterioration as opposed to a sudden event, and the affected owner's contents and belongings (that's their own contents insurance, not the strata policy).
• The excess has to be paid by someone, and who wears it can itself be a dispute — often it falls to the responsible party or the owners corporation depending on the cause and your policy.

The practical move: as soon as a leak causes real damage, notify your insurer / broker early and ask whether it's claimable before you commit to paying for make-good out of funds. But don't let an insurance question delay stopping the water — make-safe first, claim later. See Strata Insurance Explained for what the building policy does and doesn't reach.

Per-state specifics

The source-not-symptom principle is national, but the strength of the owners corporation's duty to repair common property, the timeframes, and where a stuck dispute goes are set by each state. Check the callout for your scheme.

When responsibility is genuinely shared or unclear

Some leaks refuse to resolve cleanly — the source straddles the boundary, two possible causes exist, or the investigation is inconclusive. Before it becomes a standoff:

1. Keep the make-safe going regardless. The ambiguity is about who pays, never about whether the water gets stopped. Contain and dry while you sort responsibility.
2. Commission a definitive investigation — a building consultant's report, dye or flood testing — and put its cost aside as provisional to be reallocated. A written expert opinion is worth far more than two owners' competing hunches.
3. Consider a shared interim arrangement. Where the source is genuinely split (say, common membrane and an owner's renovation both contributing), agreeing a cost split in writing, without admission, gets the repair done while the apportionment is settled.
4. Escalate early, not late. If it's stuck, use your state's dispute pathway (see the callouts) sooner rather than after months of damage. Tribunals can order the work; a stalemate can't.
5. Record every step. When it was reported, when it was made safe, who investigated, what they found, who was asked to fix what. If it ends up at a tribunal, that timeline is your case — and for the OC, the record of acting promptly is what limits liability.

Common mistakes

1. Arguing about who pays before stopping the water

The most expensive mistake there is. Every day of delay is more damage and more mould. Make-safe first; allocate cost second. The two are not the same decision and must not wait on each other.

2. Blaming the lot where the stain appears

Water shows up at the lowest point, not the source. Allocating the repair to the unit with the wet ceiling, without tracing where the water came from, is how schemes fix the wrong thing and end up doing it twice.

3. Making good the damage before fixing the source

Repaint the ceiling while the leak above is still active and you'll repaint it again. Cosmetic make-good is always the last step, after the source is fixed and the area has dried.

4. Skipping the professional investigation to save money

The leak-detection or plumber's report is the cheapest part of the whole job, because it's the step that tells you who owns every cost after it. Guessing the source to save a call-out fee routinely costs ten times more in misallocated repairs.

5. Forgetting insurance until the bill arrives

A sudden escape of water is often an insurable event under the building policy. Notify the insurer early and ask what's claimable before you commit levies to the make-good — but never let the insurance question delay stopping the water.

6. Letting a leak sit and become mould

Mould is a health issue, not just a stain, and it takes hold within days. A leak parked pending a responsibility argument can turn a plumbing bill into a remediation project and expose the scheme to liability for occupants' health.

Frequently asked questions

Water is coming through my ceiling from the unit above. Whose problem is it?

It depends entirely on the source, not the fact that it's landing in your lot. If the water comes from the upstairs owner's own bathroom waterproofing or an overflowing appliance, it's likely theirs; if it comes from common structure, a common pipe, or a failed common balcony membrane above you, it's the owners corporation's. The first step is always to stop the water and investigate the source — nobody can fairly allocate it until that's known.

Who pays for the plumber to find the leak?

Usually one of three ways: the owners corporation fronts the investigation (common when the source is likely common property or crosses lots), the affected owner fronts it and is reimbursed if the source turns out to be common property, or the cost is split until the source is found. The key is that someone commissions it quickly and the cost is treated as provisional, to be reallocated to whoever owns the source.

The leak damaged my furniture and carpet — will strata insurance cover it?

The strata building policy generally covers building damage (ceilings, walls, fixtures) from an insured event, subject to the excess. Your personal contents — furniture, belongings, and often floor coverings you installed — are typically not covered by the strata policy; that's what your own contents insurance is for. Check the specific policy and raise it with the broker early.

The owners corporation is dropping its feet on a common-property leak. What can I do?

In most states the OC has a legal duty to repair common property, and in NSW that duty is strict enough that owners have won damages for delay. Report it in writing, keep a dated record of every follow-up, and if it stays unaddressed, use your state's dispute pathway — Fair Trading/NCAT in NSW, the BCCM Commissioner in Queensland, Consumer Affairs/VCAT in Victoria, SAT in WA — to seek an order that the work be done.

It's a musty smell and a damp wall but no obvious leak. Is that still the scheme's problem?

Not necessarily — it may be condensation (poor ventilation, no exhaust fan, drying washing indoors), which is usually the occupant's to manage, or rising/penetrating damp through the building fabric, which is usually common property. A proper moisture investigation distinguishes an active leak from condensation before anyone opens a wall. Don't assume every damp patch is a burst pipe.

Quick checklist

• [ ] The water has been stopped and the area made safe — before any argument about responsibility
• [ ] Wet floor coverings and contents are protected and drying to limit damage and mould
• [ ] A plumber or leak-detection specialist has been engaged to find the source
• [ ] The source is identified and matched to the property boundary and the who-it-serves rule
• [ ] Responsibility for fixing the source is allocated to whoever owns it
• [ ] The insurer / broker has been notified early where there's real damage, and you've asked what's claimable
• [ ] Make-good of the damage happens after the source is fixed and the area has dried
• [ ] Every step is dated and recorded — report, make-safe, investigation, allocation — in case it's disputed

Related resources

• Common Property vs Lot Property: Who's Responsible for What?
• Handling a Common Property Repair: From Report to Resolution
• Strata Insurance Explained: What Your Scheme Must Cover, and What It Doesn't

This guide is general information for self-managed strata schemes in Australia. It is not legal advice. Responsibility for water leaks depends on your scheme's registered plan, the strata legislation and regulation that apply in your state, your by-laws, and the specific source of the water — always trace the source, check the plan and your insurance policy, and seek professional advice on genuinely borderline or high-value leaks.