Nuisance and the importance of evidence

The Scottish courts have recently considered a complaint made by an individual about odours emitted from a nearby waste water treatment plant. This article discusses the court's view on the evidential burden on those complaining of 'nuisance', and the evidence required in support of the complaint.

24 June 2020

The Scottish courts have recently considered a complaint made by an individual about odours emitted from a nearby waste water treatment plant. The case demonstrates the high evidential burden on those complaining of nuisance, and the importance of having cogent, independent evidence in support of the complaint.

The legal test for nuisance

We recently considered the legal test for nuisance here. In summary, the owner or occupier of a property must not use their land in a way that disturbs their neighbour's enjoyment of the property, or which causes damage to it. Importantly, the nuisance must be continuing and the complainer must have suffered more than they could reasonably be expected to tolerate (known as the 'plus quam tolerabile' test). The nuisance must cause more than mere discomfort to the complainer.

The court will take a number of facts and circumstances into account when considering whether the plus quam tolerabile test is met, including the impact and extent of the nuisance, the importance of the action causing the nuisance complained of, and whether steps can be taken to prevent it.

MacBean v Scottish Water [2020] CSOH 55: the background

In 2015, a waste water treatment plant (the “plant”) operated by Scottish Water became operational, and began to emit fumes into Mr MacBean’s garden. Mr MacBean complained that the odours from the fumes were disrupting his enjoyment of his property, and subsequently brought the case to court seeking interdict to stop the nuisance continuing, and damages.

Scottish Water conceded that it had been causing a nuisance, however at a preliminary hearing, interdict was not granted and Scottish Water was given the opportunity to make improvements. At the most recent hearing in March 2020, Scottish Water argued that it had undertaken sufficient remedial works to reduce the extent of the odours so that there was no longer a nuisance. It also argued that the public utility of the plant, the adverse consequences of it ceasing to operate, and the high cost of constructing a replacement plant at another site (the plant in question cost more than £5 million to construct) were relevant factors that the court should take into account when assessing whether the plus quam tolerabile test was met. Mr MacBean disagreed, and argued that the nuisance remained.

Remedial works

As part of the remedial works that it undertook to deal with the odours, Scottish Water fitted carbon filters to air vents, manhole covers and septic tank covers, sealed covers for the chemical dosing hose inlet, and, most importantly in the eyes of the court, installed an Odour Control Unit ("OCU") in September 2019.

There was conflicting expert evidence on the effectiveness of the carbon filters and other remedial works, however there was significant and consistent evidence regarding the function of the OCU. In early 2019, Scottish Water commissioned engineers from two companies to act as assessors, taking measurements of the odour and the presence of noxious hydrogen sulphide at 10 different points in the locality of the plant (five within the plant site, and five just outside).

The assessors took these measurements on a daily basis throughout 2019, and found a marked reduction in presence of odours following the installation of the OCU in September 2019. The assessors who gave evidence during the hearing also consistently said that odours had been “faint, localised and intermittent”, The one exception was during desludging operations, when there had “occasionally” been more persistent odours. They also noted odours coming from fertiliser that was being used on a nearby farm, and a bonfire in a neighbour’s garden.

Nuisance or no nuisance?

The court considered two questions: firstly, were there still odours coming onto Mr MacBean's property from the plant; and secondly, was the plus quam tolerabile test met?

The court, and the parties, accepted that there were still odours coming onto Mr MacBean’s property. The dispute therefore focused on answering the second question.

The court considered in detail the evidence presented by each of the parties. The assessors commissioned by Scottish Water were seen by the court to be independent; they had used a “systematic and exacting” methodology and kept detailed records of their findings, had taken measurements over many months, and were consistent in their conclusions that the OCU had resulted in a reduction in odours coming from the plant.

In contrast, the evidence in support of the existence of the nuisance was “anecdotal”. Some of the witnesses were only occasional visitors, and therefore were not in a position to comment on whether the odours were consistently present. The court also commented that the main source of evidence in support of Mr MacBean's case was Mr MacBean himself, and that there was a lack of independent evidence produced in support of the existence of the nuisance. The consistent scientific evidence put forward in support of Scottish Water's case was therefore preferred, and the court held that the odours that were still omitted by the plant were “irregular, faint, transient, and only occasionally go on to Mr MacBean's property”.

The court also placed significant weight on the steps taken by Scottish Water to resolve the issue since the second hearing, at which it was decided that there was a nuisance, the fact that the plant “performs an important public service” and that it would be disruptive to shut it down or ask Scottish Water to move the plant elsewhere.

The court decided that based on the scientific evidence, Mr MacBean could reasonably be expected to tolerate the odours. There was therefore no longer a nuisance.

Key takeaways

This decision highlights that the plus quam tolerabile test can be a difficult one to satisfy, particularly in the face of scientific evidence suggesting that the consequences of the act complained of are not sufficient to conclude it is intolerable. Strong, consistent, and preferably independent evidence in support of the complaint may assist in successfully establishing that the legal test has been met and that an act constitutes a nuisance. Anecdotal evidence is unlikely to be enough, although each case will turn on its own facts and circumstances.

It also demonstrates that courts may look favourably upon parties who are the subject of complaints who have taken reasonable steps to resolve the issue, particularly if that party can show that the steps in question made a noticeable difference in dealing with the act complained of.

If you would like to find out more about nuisance, please contact Elaine Brailsford ( or Stephanie Hepburn ( You can also watch our recent webinar on the subject here.

Additional reporting by Alec Fair.