Drainage Easement Rights in NSW: What Can You Actually Do on Your Neighbour’s Land?

I have the benefit of a drainage easement over my neighbour’s property – what can I actually do on their land?

If you are a property developer or landowner who owns land with the benefit of a drainage easement over an adjoining property, you may have wondered exactly what that easement entitles you to do on their land (particularly if you are experiencing opposition from your neighbours regarding works on their land.

The recent decision of the Supreme Court of New South Wales in McLennan v Ng [2025] NSWSC 1429 provides some helpful practical guidance on this question, and confirms that the rights conferred by a standard form “easement to drain water” are broader and more robust than many servient landowners might expect.

The dispute in McLennan v Ng concerned two properties in Pennant Hills, Sydney. The plaintiffs, the McLennans, owned land on a hill (Lot 212) that benefited from a 1.2 metre wide “easement to drain water” over the defendant’s lower-lying property (Lot 208). The easement had been created on registration of the deposited plan in 1988 pursuant to section 88B of the Conveyancing Act 1919. Within the easement sat an old 90mm clay pipe, installed before 1989, which had deteriorated badly over 36 years. CCTV inspections revealed it was in poor condition with tree root intrusion and cracking.

The McLennans wished to subdivide their lot and, as a condition of development consent granted by the Hills Shire Council, needed to upgrade the stormwater drainage infrastructure passing through the easement on the defendant’s land. This is an increasingly common requirement imposed by councils at present – many councils are not even accepting development applications for lodgement with at least an in-principle agreement being in place for a drainage easement (if not a fully registered easement!).

The proposed works were fairly substantial:

• replacing the existing pipe with a 225mm PVC pipe across the full length of the easement;
• excavating along its length;
• backfilling; and
• installing a precast junction pit and additional stormwater pits all within the 1.2 metre wide easement corridor.

The defendant, Ms Ng (owner of Lot 208), objected to the above works on several grounds:

• that the easement did not permit laying a new, larger pipe where one already existed;
• that stormwater pits were not covered by the easement;
• that the proposed pipe size represented an impermissible intensification of use; and
• that the requirement to remove five trees and various structures on her land went beyond what the easement allowed.

The Court held comprehensively in favour of the McLennans. His Honour construed the standard form “easement to drain water” (the terms of which are implied by section 181A of the Conveyancing Act) as conferring three distinct rights:

1. a full and free right to drain water in any quantities across and through the servient tenement;
2. the right to use any existing line of pipes or “any pipe or pipes in replacement or in substitution therefor,” and where no pipes exist, to lay and maintain pipes of sufficient internal diameter; and
3. the right to enter the servient tenement with tools, implements or machinery to lay, inspect, cleanse, repair, maintain or renew the pipeline, and to open the soil to such extent as may be necessary — subject to taking all reasonable precautions to ensure as little disturbance as possible and restoring the surface as nearly as practicable to its original condition.

Critically, the Court confirmed that the dominant owner has the right to determine the size of the replacement pipe, so long as it is reasonably necessary to serve the drainage purpose. The fact that the new 225mm pipe was significantly larger than the existing 90mm pipe did not take it outside the scope of the easement. Richmond J cited the English authority of Simmons v Midford [1969] 2 Ch 415, in which Buckley J held that “the right to lay pipes under the servient strip is not confined to a single pipe or to a pipe or pipes of any particular kind or dimension.” His Honour also relied upon the earlier New South Wales decision of Bland v Levi [2000] NSWSC 161, in which the Court held that the dominant owner may do work on the servient tenement which is reasonably necessary for enjoyment of the easement and that “the right to decide what works will be done, what is the thickness of the driveway and the like, are part of the rights that are granted to the dominant owner and are a matter for it alone.”

This decision also confirms that ancillary rights (i.e. those implied into the easement as reasonably necessary for its exercise or enjoyment) extend beyond the bare text of the grant. Although the standard form easement refers only to laying pipes, the Court held that the installation of a stormwater drainage pit was permitted as an ancillary right, because expert evidence confirmed it was reasonably necessary for the effective exercise of the right to drain water. This principle derives from the High Court’s recognition in Westfield Management Ltd v Perpetual Trustee Company Ltd (2007) 233 CLR 528 that the grant of an easement carries with it those ancillary rights which are necessary for the enjoyment of the rights expressly granted.

One of the most significant aspects of McLennan v Ng that every developer and landowner should pay attention to is its treatment of obstructions placed on the easement by the servient owner. Ms Ng had constructed stone paving, retaining walls, a garden bed and installed an air-conditioning unit over the easement area. Richmond J held that the dominant owner is entitled to remove, or require the removal of, these obstructions if necessary to install the new pipe, relying upon the earlier Court of Appeal decision in GM Amalgamated Investments (Dulwich Hill) Pty Ltd v Mills [2014] NSWCA 202, in which the Court held that the construction of concrete paving over an easement would constitute a “significant impediment” to the exercise of the easement rights and that “the Dominant Owners are entitled to require the Servient Owner not to make the exercise of the rights conferred by the Easement practically impossible or substantially more difficult.” Richmond J further held that “original condition” (to which the surface must be restored after the works are complete) refers to the condition immediately before the works are done, not the condition at the time of the original grant of the easement.

The decision also broke new ground (pun intended) on the question of trees. Five trees on Ms Ng’s property had their trunks located outside the easement but their root systems (between 30% and 55%) extended into the easement corridor, damaging the existing pipe and impeding installation of the new one. Richmond J held that the Court could order their removal notwithstanding that their trunks were outside the servient tenement, because the root intrusion constituted a substantial interference with the exercise of the easement rights. His Honour drew support from the English decision of Bockenfield Aerodrome Ltd v Clarehugh [2021] EWHC 848 (Ch), where the Court ordered the removal or reduction in height of trees on a servient tenement that interfered with an easement of overflight benefiting an adjacent airfield, demonstrating that the Court’s power to restrain substantial interference can extend to requiring positive action by the servient owner against obstacles — even those located technically outside the easement boundaries.

A further practical issue addressed in McLennan v Ng is the increasingly common problem of the servient owner’s refusal to consent to development applications lodged by the dominant owner. Local council had required Ms Ng’s written consent to the McLennans’ section 68 application for construction approval. Her refusal to provide it was held to constitute a substantial interference with the McLennans’ rights under the easement, and the Court held it could grant an injunction requiring consent. This follows the well-established line of authority including Sertari Pty Ltd v Nirimba Developments Pty Ltd [2007] NSWCA 324, in which Handley AJA held that “the servient owner’s refusal of consent, where this is legally necessary, obstructs the dominant owner in the exercise of rights under the easement” and that “obstruction by legal means in this way is just as much an infringement of the dominant owner’s rights as a direct physical obstruction.” This principle was recently affirmed by the Court of Appeal in Owners Corporation Strata Plan 533 v Random Primer Pty Ltd [2025] NSWCA 8, where Kirk JA held that the ultimate question is whether the refusal of the servient owner to give consent constitutes a substantial interference in the rights of the dominant owner, assessed as a “practical, evaluative judgment about neighbours being able to exercise their respective property rights.”

I have been looking forward to writing this article for nearly six months in light of the ramifications that this decision has for anyone who owns property benefiting from or burdened by a drainage easement (or any similar easement such as an easement for services or even a right of carriageway), as McLennan v Ng confirms that the holder of a standard form drainage easement in New South Wales possesses robust rights:

• to replace existing pipes with larger ones;
• to install ancillary infrastructure such as stormwater pits;
• to excavate and open the soil;
• to remove obstructions — even long-standing ones — placed on the easement by the servient owner;
• to require removal of trees whose roots interfere with the easement, even where their trunks sit outside the easement boundary; and
• to compel the servient owner to consent to necessary development applications.

These rights are subject to the important proviso that the dominant owner must take all reasonable precautions to minimise disturbance and must restore the surface of the servient tenement as nearly as practicable to its condition immediately prior to the works. As Thomas v Pearson [2025] NSWSC 1127 reminds us, the scope of any easement ultimately depends upon a proper construction of the grant in light of its text, context and purpose — but for those holding the benefit of a standard form drainage easement, McLennan v Ng makes clear that the rights are extensive and the Courts will enforce them.