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Drainage systems don’t always stop at the boundary line. In many Sydney suburbs, older homes share sewer or stormwater connections. Tree roots spread across fences, and pipes often run beneath more than one block. When those pipes clog, the effects can spill into your property even if the source is next door.
Blocked drains are inconvenient at best and damaging at worst. They can leave you facing water pooling in the yard, foul odours indoors, or even sewage backing up through toilets and sinks. If the problem starts on a neighbour’s property, frustration quickly follows. The right approach is a mix of identifying the source, addressing it fairly, and calling in professionals when required.
Not every blockage originates inside your own system. Some clues indicate that the trouble is coming from across the fence line.
Common warning signs:
Gurgling and sewer smells are often early indicators. If you notice these changes, it’s worth considering whether a neighbour’s pipes are the source. Our guide on gurgling drains and sewer back-ups as early warning signs goes deeper into why these sounds and smells shouldn’t be ignored.
Shared pipes and close planting often lead to blockages that don’t respect property lines. We’ve seen many Sydney households face the same repeating causes:
| Cause | How it spreads across properties | Typical outcome |
| Tree roots | Roots search for water, breaking into joints and pushing through pipe walls | Clogged or collapsed stormwater/sewer lines |
| Old shared connections | Ageing clay pipes often run under two or more homes | Grease, wipes, or silt backing up both ways |
| Mismanaged stormwater | Incorrect downpipe connections or poor grading | Pooled water flooding the neighbour’s yard then yours |
Roots are the most common culprit. They don’t respect fences and often enter from a tree that isn’t even on your side. That’s why we often remind customers that tree roots invading stormwater pipes can cause long-term damage unless treated early. Recent figures from SA Water highlight the scale of the problem, with more than 5,100 sewer main blockages recorded in 2024-25, and tree roots responsible for nearly two-thirds of those cases.
Before approaching your neighbour, it helps to be certain the blockage isn’t within your own system. A few simple checks can narrow it down:
If you’ve already tried household remedies without success, it can help to refer back to our practical guide to clearing blocked drains. That way, you can rule out simple fixes before pointing to a cross-boundary issue.
Telling a neighbour that their property is affecting yours can feel uncomfortable, but clear communication makes all the difference. Keep it factual and avoid blame.
A good approach is:
Sometimes, neighbours are unaware of the problem until you raise it. A calm conversation often resolves the matter faster than escalating it to council.
Responsibility usually falls to the property owner where the blockage originates. If tree roots from their yard are confirmed as the cause, or if their connection is defective, they may need to arrange the repairs. Councils can step in when disputes arise, particularly where shared lines or street connections are involved.
Sydney Water also has authority over public sewers. If a main sewer is involved, they will manage the repair directly. Homeowners remain liable for private pipes up to the point they connect with the public line.
Online discussions highlight how divided opinions can be. In one Whirlpool forum thread, homeowners argued over liability after roots crossed a boundary. One user described how the Water Authority carried out repairs at the boundary trap but required the neighbour to cover the cost of tree removal. These types of experiences show how outcomes often depend on the exact location of the damage and who holds responsibility for the offending tree.
For disputes that escalate, plumber reports and CCTV footage often form the evidence councils require. Keeping those records can save time and avoid unnecessary back-and-forth.
Household remedies often reach their limit once roots, collapsed joints, or heavy grease build-ups are involved. At that point, professional equipment and expertise are the only way forward.
A licensed plumber can:
We regularly see people attempt repeated chemical or mechanical fixes without results. If water is starting to back up indoors, the urgency matches that of a blocked toilet situation. Leaving it untreated only increases the risk of flooding and property damage. In many cases, the safest path is recognising when to call a professional for blocked drains rather than trying the same methods again.
Prevention requires a mix of regular checks and proactive upgrades. Some actions are simple, others require investment, but all reduce the likelihood of recurring disputes.
Preventive options:
Weather events can also trigger issues. After heavy rainfall, stormwater often carries silt and leaves into shared lines. That’s why it helps to be aware of how drains often clog after heavy rain, even when both households maintain their systems.
Money often complicates neighbourly disputes. Costs depend on where the blockage originates and which property suffers the damage.
Insurance policies sometimes cover sudden damage but rarely cover gradual root intrusion. For that reason, a clear plumber’s report matters. It establishes liability and speeds up claims where applicable.
A simple table helps clarify the difference between quick fixes at home and full plumbing intervention:
| Approach | Suitable for | Limits |
| Boiling water, plungers, basic drain cleaner | Small localised clogs | Won’t clear roots, collapsed joints, or major grease |
| Hardware store drain snakes | Short sections of pipe | May damage pipes, often temporary |
| Professional jet blasting | Heavy grease, silt, minor root growth | Requires specialist equipment |
| CCTV inspection + relining | Recurrent or severe blockages | Involves cost, but offers long-term protection |
Attempting to save on immediate costs often leads to repeated problems. Investing in a professional fix provides certainty and reduces conflict with neighbours.
One Sydney household we worked with faced repeated flooding in their laundry. CCTV inspection revealed that a large gum tree on the adjoining property had penetrated the sewer. The neighbour initially denied responsibility until shown video footage. With evidence in hand, both parties approached the council, which confirmed the liability. The neighbour arranged for root removal and contributed to pipe relining costs.
From our experience, these disputes often stall until hard evidence is presented. We’ve found that video inspections are usually the turning point, giving homeowners something concrete to take to their neighbour or council. Once the facts are visible, conversations shift from argument to resolution. Clear records in this case turned what could have been a drawn-out conflict into a straightforward outcome.
Tone matters as much as facts. A heavy-handed approach often leads to arguments, while a cooperative one encourages shared solutions.
Effective strategies:
Most homeowners prefer to fix a problem once they realise it also affects them. If the first approach fails, having evidence ready for council speeds up the next stage.
Local councils usually intervene only after neighbours fail to reach agreement. They rely on evidence to assign responsibility. Sydney Water, on the other hand, manages sewer mains and will repair faults in their network without charge.
Key points to keep in mind:
Having a professional inspection done early provides leverage and avoids drawn-out arguments.
Plumbing issues can strain even the best neighbourly ties. Long-term cooperation reduces the chances of repeat disputes. Small steps such as agreeing to regular inspections or jointly funding pipe relining can prevent years of future conflict.
For neighbours willing to invest together, it often costs less to upgrade shared lines once than to pay for repeated clear-outs separately. Open communication paired with professional input creates durable outcomes.
Blocked drains caused by neighbouring properties present both technical and personal challenges. Pipes don’t respect fences, and neither do tree roots. Problems often require a mix of careful diagnosis, calm discussion, and skilled intervention.
At Graham & Sons Plumbing, we’ve assisted countless Sydney homeowners through these exact situations. From evidence gathering to final repairs, our focus is always on protecting your home while supporting a fair resolution. If you’re facing recurring issues linked to next door, a professional assessment is the best starting point.
Call us today for inspections, reports, or emergency repair — our licensed team is available across Sydney to help you regain peace of mind.
* Between 8.30am - 5.00pm, Monday to Friday.
