I am experiencing excessive stormwater discharging from my uphill neighbour’s property – is this a legal ‘nuisance’ that might be actionable in Court?

As we experience an increase in severe weather events and 1 in 100-year rainfall/flooding events (also known as 1% annual exceedance probability, or AEP, events) become more common, I am finding more and more clients are coming to me with complaints about the volume of stormwater being discharged onto their property from adjoining high ground, usually a neighbouring residential lot.

However, there is no simple (or inexpensive) way for a downhill property owner to abate this stormwater discharge on the grounds of the discharge constituting a nuisance if the uphill neighbour does not wish to take steps to address the issue. You may need to approach the Court to seek relief.

What exactly is a private nuisance, and does flooding count as a nuisance?

Nuisance is a common law tort actionable in the Supreme Court of NSW. You can ask the Court for a declaration that someone has substantially/unreasonably interfered with or disturbed your ordinary/reasonable use of your land (usually without actually entering your land) on the basis that a private nuisance has occurred, and can seek relief in respect of that nuisance in the form of your neighbour being ordered to carry out remedial work and/or pay you damages.

While a lower landowner must accept the “natural flow” of surface water from higher ground, an upstream owner cannot deliberately channel, concentrate, or alter that flow in a way that causes substantial damage to the lower neighbour.[1] If your neighbour constructs something (like a pool, driveway, or retaining wall) that changes the natural flow of water, the burden shifts to your neighbour to show they did not cause an actionable nuisance.[2]

The High Court has recently handed down a decision[3] that definitively states what private nuisance is (and also what it is not) – it isn’t just an enquiry into negligence on the part of one person or another. An interference with the use and enjoyment of land must be both substantial and unreasonable in order to constitute a private nuisance that is actionable in Court, and there must be a balance between the right of the occupier to do what he likes with his own land and the right of his neighbour not to have his land interfered with.

So what does this look like in terms of stormwater discharge? Some recent decisions in various NSW Courts are helpful to look at, and I’ve prepared a table comparing the decisions that should help you if you are experiencing excessive stormwater discharge from a neighbouring property and are considering your options.

Rifai v Woods [2024] NSWSC 374 – Nuisance Established

The Rifais sued their neighbours, the Woods, for private nuisance arising from stormwater and pool water flowing from the Woods’ higher property (No. 47) onto the Rifais’ lower property (No. 49) in Glenmore Park. The Court (Peden J) found that the Woods installed a replacement drainage system that did not comply with relevant Australian standards and did not effectively drain stormwater or pool water to the street. Pool water overflow and leakage also constituted a nuisance because pool water should be treated as sewerage and drained to the sewer, not a stormwater system.

The Woods failed to establish the defence that the water nuisances involved no more than the reasonable and convenient use of their land. Injunctive relief was granted requiring the Woods to rectify drainage defects and pool issues.

Boyes v Thomson [2024] NSWSC 1325 – Nuisance Not Established

The Boyes alleged that stormwater runoff from their neighbour Thomson’s higher property constituted a private nuisance by reason of a defective inter-allotment drainage system (IAD). Peden J accepted that during particular extreme weather events in 2019–2022, large amounts of water entered the Boyes’ land and caused a material and unreasonable interference. However, the Boyes accepted that Thomson did not create the nuisance.

The Court held that Thomson had not adopted the nuisance because he had taken reasonable steps (including beneficial works such as turf, retaining walls, water tanks and logs) within a reasonable time to bring the nuisance to an end. No evidence demonstrated that excessive water was presently flowing from Thomson’s land. The claim for damages was also dismissed because the Boyes failed to establish any recoverable loss.

Tannous v Tang [2025] NSWDC 529 – Nuisance Established

Tannous sued the Tangs in the District Court for nuisance caused by stormwater escaping from their adjacent property (No. 2B) onto his property (No. 4) in Yagoona. The Court (Cole DCJ) found that the stormwater drainage system on the Tangs’ land and an appurtenant easement was almost completely blocked and practically non-functional, causing water to flood into No. 4 up to eight times per year since March 2021. The Tangs’ failure to maintain and repair the stormwater infrastructure was characterised as an “abrogation of their responsibility” amounting to private nuisance.

The Tangs were ordered to remedy the nuisance by repairing and reconfiguring the drainage system and to pay damages of $99,382.01. The Tangs’ cross-claim under s 177 of the Conveyancing Act 1919 regarding the removal of support provided by Tannous’s land was dismissed.

Tang v Tannous [2026] NSWCA 156 – Appeal Dismissed (Nuisance Finding Upheld)

The Tangs appealed the District Court decision I have summarised above. The Court of Appeal (Payne JA, Mitchelmore JA and Harrison AJA) granted leave but dismissed the appeal. The applicants’ (i.e. the Tangs’) central thesis, that the respondent’s (i.e. Tannous) own contractors created the gap through which 90% of stormwater entered, was rejected as based on “little more than assertion” and misstatements about the evidence.

The primary judge’s finding that the blocked stormwater pipe was the predominant cause of the damage was upheld. The argument that s 177(8) of the Conveyancing Act 1919 barred the nuisance claim was also rejected.

Owners of Strata Plan No 1954 v Ashdown Home Units Pty Ltd [2026] NSWSC 298 — Nuisance Established (Quia Timet Only)

The Owners Corporation of an apartment block in Elizabeth Bay sued Ashdown Home Units Pty Ltd, alleging that the steep slope on the defendant’s land, combined with inadequate stormwater drainage, threatened to cause the plaintiff’s retaining wall to collapse. Faulkner J found that the slope had not already moved or caused damage to the wall (a “bulge” in the retaining wall was not proven to be the defendant’s doing). However, the Court was satisfied there was a “not insignificant risk” that future saturation of the slope (caused by 76% of the defendant’s land draining down the slope through a defective system) would cause the slope to become unstable and damage the wall. The defendant’s use of its land was not natural given the failure to properly drain stormwater.

A conditional mandatory injunction was ordered requiring the defendant (Ashdown Home Units) to install a new stormwater drainage system on its uphill land (at an estimated cost of ~$30,000), conditional upon the plaintiff first obtaining any necessary easement. No damages were awarded because no past physical damage was proven – the proceedings were brought on a quia timet basis; that is, on the basis that there was a real threat of physical damage would occur (but had not yet occurred).

Comparative Table: Why Each of the Above Nuisance Claims Succeeded or Failed

Key Distinguishing Principle

The critical distinction between Boyes v Thomson (where the claim failed) and the other cases (where it succeeded) is whether the defendant took reasonable steps to address the known interference. Thomson carried out substantial beneficial works and, by the time of trial, there was no evidence of ongoing excessive water flow. In contrast, in Rifai, Tannous, and Ashdown, each defendant either created the problem through non-compliant works or allowed known drainage deficiencies to persist over years without taking meaningful remedial action, despite having knowledge of the interference.

The central distinguishing factor is whether the defendant took reasonable steps to abate the nuisance once on notice of it. Thomson did (and succeeded in his defence), while the defendants in the other cases did not.

The table of cases above shows that each circumstance was quite different but a successful nuisance claim was able to be made (with Boyes v Thomson being the outlier). You should carefully consider whether your circumstances might be similar enough to one of the four successful cases summarised above to consider making a claim against a neighbour who is causing a nuisance through their actions or omissions regarding stormwater discharge, and has failed to abate the nuisance when requested.

Please get in touch if you’d like to discuss the specifics of your case in detail.

[1] Gartner v Kidman (1962) 108 CLR 12

[2] Corbett v Pallas (1995) 86 LGERA 312

[3] Hunt Leather Pty Ltd v Transport for NSW [2025] HCA 53