Water Resources Act 1991 — Pollution Prevention for UK Businesses

The Water Resources Act 1991 (WRA 1991) is the primary statute governing the protection of surface waters and groundwater in England and Wales from pollution. Despite being supplemented by the Environmental Permitting Regulations 2016 (EPR) and the Water Framework Directive (as retained in UK law), Section 85 of WRA 1991 remains the most widely prosecuted environmental water pollution offence. This reference guide provides a comprehensive analysis of the statutory framework, applicable case law, enforcement powers, available defences, and interaction with the EPR 2016 — essential reading for any business storing, handling, or disposing of substances that could affect controlled waters.

Section 85 — The Core Offence

Section 85(1) WRA 1991 provides: "A person contravenes this section if he causes or knowingly permits any poisonous, noxious or polluting matter or any solid waste matter to enter any controlled water."

This deceptively simple provision creates one of the most powerful environmental enforcement tools available to the Environment Agency. There are two distinct limbs:

"Causing" — Strict Liability

The word "causes" imposes strict liability — there is no requirement for the prosecution to prove any fault, intent, or negligence on the part of the defendant. It is sufficient that the defendant's acts or operations were a cause (not necessarily the sole cause) of the entry of polluting matter into controlled waters. This is not a minor technical point: it means that a company that stores chemicals or oil in inadequate secondary containment can be convicted even if a pollution event was triggered by a third-party act, equipment failure, or natural event, provided the company's storage arrangement was itself causally connected to the pollution.

"Knowingly Permitting" — Knowledge Required

The second limb — "knowingly permitting" — requires that the defendant had knowledge of the entry of polluting matter and failed to take steps to prevent it. This applies particularly to situations where a pollution source is on the defendant's land but the pollution was caused by another party, and the defendant's culpability lies in inaction rather than action.

Empress Car Co v National Rivers Authority [1999] — Leading Case

Empress Car Co (Abertillery) Ltd v National Rivers Authority [1999] 2 AC 22 is the defining House of Lords authority on the Section 85 "causing" offence. Empress Car maintained a diesel storage tank in a yard that drained directly into a river. The tank had an unlocked valve on an outlet pipe. A person unknown opened the valve, and approximately 1,400 litres of diesel entered the River Ebbw Fawr. The House of Lords upheld the company's conviction, holding that:

• The question is whether the defendant's acts "caused" the pollution — not whether their acts were the sole, proximate, or immediate cause
• The intervening act of a third party (the vandal opening the valve) was not a novus actus interveniens sufficient to break the chain of causation
• The causal connection is established where the defendant has created or maintained a situation of which the polluting event was a natural consequence
• Maintaining an unsecured tank with an unrestricted outlet was itself the operative cause

The Empress Car principle means that any business storing oil, chemicals, or other potentially polluting substances has a positive duty to ensure adequate secondary containment, bunding, and access controls to prevent pollution from any foreseeable cause — including vandalism, equipment failure, and operator error. Secondary containment systems, bunds and drip trays, and appropriate drain protection are not merely good practice — they are essential legal safeguards.

Section 161 — Environment Agency Clean-Up Powers and Cost Recovery

Section 161 WRA 1991 grants the EA sweeping powers to carry out works to prevent or clean up water pollution and to recover the costs of doing so from the person who caused or knowingly permitted the pollution. Specifically, the EA may:

• Take remedial action to remove or dispose of polluting matter
• Restore controlled waters and adjacent land so far as practicable
• Recover all costs from the person responsible (Section 161(3))

Cost recovery is pursued through civil proceedings and is additional to any criminal prosecution. Clean-up costs for significant pollution incidents can reach tens or hundreds of thousands of pounds depending on the substance involved, the extent of contamination, and the receiving environment. Businesses handling fuel oils, chemicals, or other pollutants must factor this potential liability into their risk management strategy.

What Constitutes "Controlled Water"

Section 104 WRA 1991 defines controlled waters comprehensively to include:

• Relevant territorial waters: Coastal waters within 3 nautical miles of the baselines from which the territorial sea is measured
• Coastal waters: Any waters within the area between the baselines and the tidal limit of any river or watercourse, and any enclosed dock which adjoins such waters
• Inland freshwaters: Any river, watercourse (natural or artificial), lake, pond, reservoir, or similar water within England and Wales
• Groundwater: Any water contained in underground strata, including water in aquifers

Critically, the definition includes minor watercourses, drainage ditches, culverted streams, and even apparently dry channels that carry water seasonally. The fact that a watercourse is not named on a map, or appears to be a drainage ditch, does not remove it from the definition of controlled water.

Penalties

Section 85 WRA 1991 offences carry significant penalties:

• Summary conviction (Magistrates' Court): Unlimited fine; and/or imprisonment for up to 3 months
• Conviction on indictment (Crown Court): Unlimited fine; and/or imprisonment for up to 2 years

The Sentencing Council's Environmental Offences Guideline (effective July 2014) applies to WRA 1991 sentencing. Fines are calculated by reference to the offending organisation's annual turnover and the culpability/harm category of the offence. A large company in the highest culpability band could face a starting point fine of £3 million or more.

Interaction with Environmental Permitting Regulations 2016

The EPR 2016 (SI 2016/1154) operate alongside WRA 1991. Under the EPR, certain activities that discharge to or affect controlled waters require an environmental permit (or must operate under an exemption). Regulation 38 EPR 2016 creates an offence of operating a regulated facility without a permit or in breach of permit conditions. The maximum penalty under Regulation 38 on indictment is an unlimited fine and 12 months imprisonment. Where both WRA 1991 and EPR 2016 are applicable, the EA may prosecute under either or both statutes. WRA 1991 Section 85 continues to apply independently of permit status — a business that causes pollution to controlled waters is liable under Section 85 regardless of whether it holds an environmental permit for other activities.

Offence Comparison — Civil vs Criminal Liability

Enforcement Route	Legal Basis	Who Brings Action	Standard of Proof	Maximum Penalty	Cost Recovery
Criminal prosecution (summary)	S85 WRA 1991	Environment Agency	Beyond reasonable doubt	Unlimited fine; 3 months imprisonment	EA costs on conviction
Criminal prosecution (indictment)	S85 WRA 1991	Environment Agency	Beyond reasonable doubt	Unlimited fine; 2 years imprisonment	EA costs on conviction
Civil cost recovery	S161 WRA 1991	Environment Agency	Balance of probabilities	Full remediation costs (no cap)	Automatic (purpose of action)
Variable monetary penalty	Environmental Civil Sanctions Order 2010	Environment Agency	Balance of probabilities	Up to £250,000	Additional to VMP
Private civil claim	Common law nuisance/negligence/Rylands v Fletcher	Third party (e.g., landowner)	Balance of probabilities	Unlimited damages	Claimant's costs if successful

Defences

Emergency discharge (Section 89(1) WRA 1991): A statutory defence applies where the act constituting the offence was carried out in an emergency to avoid danger to life or health, provided the person took all reasonably practicable steps to minimise the extent of the entry or discharge and particulars were reported to the EA as soon as reasonably practicable. The burden of proving the defence rests on the defendant, and courts scrutinise whether adequate preventive measures (bunding, spill kits, containment) could have prevented the pollution from arising in the first place.

EA consent (Section 89(4)): A discharge authorised by an EA consent or environmental permit is not an offence. Businesses that need to discharge to controlled waters must obtain appropriate authorisation in advance.

Duty to Report Under Regulation 38 EPR 2016

Where an environmental permit or exemption is held, any non-compliance — including an unexpected release or spillage — must be reported to the EA under permit condition and under the EPR. Reporting should occur as soon as practicable and in any event within the timescale specified in the permit (typically within 24 hours for significant incidents, immediately for major releases). Proactive reporting is a significant mitigating factor in EA enforcement decisions and can be the difference between a civil sanction and criminal prosecution.

Maintaining appropriate spill response equipment and trained staff capable of activating emergency containment procedures within minutes of a spill occurring remains the single most effective risk mitigation for WRA 1991 liability.

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Last reviewed: April 2026