Southern Water Authority v Pegrum [1989] Crim LR 442
Causation – Novus Actus Interveniens – Act of God – Negligence – Foreseeability
Facts
The defendants were pig farmers. Waste and effluence from the pigs was stored first in tanks which drained into a lagoon which had been constructed to store pig effluence. After heavy rain a blocked drain caused excess water to flow into the lagoon. This caused a fissure in the wall of the lagoon and eventually effluence overflowed and polluted a nearby stream. The defendants were charged with an offence under s31(1) Control of Pollution Act 1974 of causing polluting matter to enter a stream. The magistrate found the water ingress to be an Act of God and the blocked drain to break the chain of causation. The prosecutor appealed.
Issues
Did the defendant’s negligence cause the pollution? Should the defendants have inspected the drain? Did the effect of the blocked drain which caused the fissure and overflow constitute an Act of God and so result in a novus actus interveniens which broke the chain of causation between the defendant’s act and the resulting damage?
Held
The appeal was allowed and the defendants remitted with a direction to convict. The defendants were liable under the provisions of the governing act if they ‘caused’ the escape of the effluence and polluting material. The question of causation was to be considered in a common sense manner, and the defendants could have ‘caused’ the escape even without their negligence. Whist an Act of God was a defence applying Rylands v Fletcher (1868) LR 3 HL 330 this act must be of such an overpowering nature that it could be said that the defendants’ conduct was not a cause at all but part of the surrounding circumstances. This was not the case. Neither the unusually heavy rain nor the blocked drain were so unforeseeable circumstances to excuse the defendants’ conduct.
Updated 20 March 2026
This case summary remains broadly accurate. Southern Water Authority v Pegrum [1989] Crim LR 442 is a recognised authority on causation and the Act of God defence in the context of water pollution offences. The article correctly identifies the relevant principles, including the common sense approach to causation and the high threshold required for an Act of God to break the chain of causation.
One material point for readers to note: the statutory provision under which the defendants were charged, section 31(1) of the Control of Pollution Act 1974, has been repealed and replaced. Water pollution offences of this nature are now governed primarily by the Water Resources Act 1991 (as amended), particularly section 85, which has itself been supplemented by the Environmental Permitting (England and Wales) Regulations 2016 (SI 2016/1154). The underlying common law causation principles discussed in the case remain applicable under the successor legislation, and the case continues to be cited in that context. Students should refer to current statutory provisions rather than the 1974 Act when researching the law as it stands today.
