The discharge of polluting effluent into a privately owned watercourse is an actionable nuisance at common law if the pollution interferes with the owner’s use or enjoyment of its property. The Water Industry Act 1991 does not exclude common law rights of action in nuisance or trespass.
The Supreme Court has allowed the canal company’s appeal in Manchester Ship Canal Co Ltd v United Utilities Water Ltd (No 2) [2024] UKSC 22; [2024] PLSCS 121.
The case concerned discharges of foul water contaminated with untreated sewage into the Manchester Ship Canal. United Utilities is the statutory sewerage undertaker for the North West. Its network includes around 100 outfalls from which material emanating from sewers, treatment works and pumping stations is discharged into the canal. When the system is operating within its hydraulic capacity the discharges are of surface water or treated effluent, but when that capacity is exceeded some of the outfalls discharge foul water into the canal. The discharges were not due to negligence or deliberate wrongdoing but they could be avoided by investment in improved infrastructure and treatment processes.
The canal company threatened a claim for trespass and nuisance, and United Utilities sought a declaration that such a right of action was barred by the statutory scheme for regulating sewerage under the Water Industry Act 1991. The High Court made such a declaration and was supported by the Court of Appeal.
The starting point for the Supreme Court was the property right vested in the owner of a canal or watercourse. This includes a right, protected by the common law, to preserve the quality of the water. A statute will only authorise what would otherwise be an unlawful interference with property rights or deprive a person from their right to bring a legal claim if it is clear from or a necessary implication of the express language used. Parliament will not be taken to have intended that statutory powers should be exercised in a way which interferes with private rights unless the interference is inevitable.
Common law rights to protect property interests survive in the 1991 Act: a sewerage undertaker is not authorised to convey foul water into a watercourse and the exercise of function so as to create a nuisance is prohibited (section 117); the availability of arbitration over water quality, at the option of the complaining party, would have no purpose unless a common law remedy is available (section 186). Parliament did not intend to exclude the enforcement of private property rights in a watercourse, which would have been a substantial change in the law.
Louise Clark is a property law consultant and mediator
