Pollution exclusion

Category: Policy exclusions · Reviewed by the Apex broking team · Last reviewed 2026-08-22 · ~5 min read

How the clause is normally built

The typical UK public and products liability wording excludes liability arising from pollution or contamination, and then writes a carve-back for pollution caused by a sudden, identifiable, unintended and unexpected incident occurring in its entirety at a specific time and place during the period of insurance. Each limb does work. Sudden and unexpected exclude the slow and the foreseeable. Identifiable requires the insured to point to an event. In its entirety at a specific time and place defeats a claim built on repeated small escapes. And during the period of insurance ties the incident, not the discovery, to the policy year.

Sudden and accidental versus gradual

The practical divide is between a tank that ruptures and a tank that weeps. A ruptured tank is a discrete incident with a time and a place; the carve-back is engaged. A tank whose seals have been failing for two years, contaminating soil that is only discovered on a site survey, is gradual pollution — and outside cover, however unintended it was. The same logic catches historic contamination inherited with a site, drift from routine operations, and any pollution whose start date cannot be pinned to a day. This is the gap addressed by gradual pollution insurance.

The clean-up cost problem

Even where the carve-back applies, a second issue arises: liability policies indemnify against damages, and statutory clean-up costs may not be damages. In Bartoline Ltd v Royal & Sun Alliance Insurance plc [2006] EWHC 3598 (QB) a fire at a chemical manufacturer’s site sent contaminants and firefighting foam into nearby watercourses. The Environment Agency carried out emergency works under the Water Resources Act 1991 and sought its costs. The High Court held that those statutory costs were not “damages” under the public liability policy: the Agency was acting in the public interest and its claim was for a debt, whereas damages in English law are generally awarded for breach of a duty or obligation. The market response was to offer express extensions covering statutory clean-up costs, but they are extensions — they have to be bought, and their limits are usually modest.

Where the exclusion sits in other classes

Pollution wording is not confined to general liability. Professional indemnity policies carry their own pollution exclusion aimed at liability for contamination rather than for advice about it, which is a distinction worth reading carefully for environmental consultants and engineers — see pollution exclusion in PI. Property policies exclude contamination as a cause of damage while sometimes covering resulting damage. Marine and energy wordings use their own regimes, covered under marine pollution insurance and oil pollution insurance.

What environmental impairment liability picks up

Environmental impairment liability insurance is written for exactly what the liability pollution clause removes. EIL wordings typically cover gradual and historic pollution as well as sudden events, statutory clean-up and remediation costs including obligations under the environmental damage regimes, on-site as well as third-party contamination, biodiversity and natural resource damage, associated legal defence costs, and business interruption arising from a pollution incident. Cover is usually written on a claims-made and discovery basis with a retroactive date, which makes the timing of purchase — and continuity of purchase — important. Related covers are set out under polluter liability insurance and environmental restoration insurance.

Who should be checking this

Any business with fuel or chemical storage, any manufacturer with process effluent, contractors working on contaminated or previously industrial land, waste and recycling operators, farms, garages and fuel retailers, and any business acquiring or leasing a site with an industrial history. For contractors the exposure often arrives with the contract, not with the premises: JCT and NEC forms allocate environmental obligations that a public liability policy alone will not answer.

Why it matters

The pollution clause is the clearest example in commercial insurance of a policy that appears to cover a risk and covers only its rarest form. Sudden incidents are the minority of pollution losses; gradual contamination and regulatory remediation are the majority, and they sit outside the standard wording by design. Buying EIL is a deliberate decision, not a default.

Frequently asked questions

Does my public liability policy cover pollution?

Usually only pollution caused by a sudden, identifiable, unintended and unexpected incident occurring in its entirety at a specific time and place during the period of insurance. Gradual or historic contamination falls outside that carve-back.

Are Environment Agency clean-up costs covered?

Not automatically. In Bartoline Ltd v Royal & Sun Alliance Insurance plc [2006] EWHC 3598 (QB) the court held that statutory clean-up costs recovered by the Environment Agency were a debt rather than “damages” under a public liability policy. Express clean-up cost extensions are available but have to be bought.

What does environmental impairment liability add?

EIL is designed for what the liability pollution clause removes: gradual and historic pollution, statutory remediation, on-site contamination, biodiversity damage, defence costs and related business interruption.

Related entries

• Environmental impairment liability insurance
• Gradual pollution insurance
• Pollution exclusion in PI
• Polluter liability insurance
• Environmental restoration insurance

This entry is part of the Apex Insurance Wiki. Last reviewed 2026-08-22. Next review: 2027-02-22. It is general insurance information, not legal advice, and it describes UK market practice and law as at August 2026.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This page is general information, not advice on a specific policy.