On 11 and 12 February 2026, the Court of Appeal is hearing Professor Carolyn Roberts' appeal against the Competition Appeal Tribunal's judgment dismissing her applications to certify parallel opt-out collective proceedings brought against six water and sewage companies (the Defendant Companies).
The claims alleged that the Defendant Companies had abused their monopoly positions for providing water and sewage services to household customers in their geographic area by underreporting the number of pollution incidents to their regulator, the Water Services Regulation Authority (Ofwat). The claims alleged that this enabled the Defendant Companies to charge higher prices to customers than they would have been able to charge had they made accurate reports. The claims for aggregate damages comprised the difference between the amounts that consumers paid and the lower amounts that the Defendant Companies would have charged had they made accurate reports.
The Tribunal's decision
The Tribunal refused to certify Professor Roberts' claims on the basis that they were excluded by section 18(8) of the Water Industry Act 1991 (WIA), which effectively provides an exclusive remedy in respect of contraventions of certain statutory obligations under the WIA. It was common ground that the underreporting of pollution incidents was one such obligation, so the key question for the Tribunal was whether section 18(8) excluded the common law remedy for an abuse of dominance claim.
In concluding that the claims were excluded, the Tribunal relied on the Supreme Court decision in United Utilities Water Ltd v Manchester Ship Canal Co Ltd (No 2) [2024] UKSC 22 (United Utilities). In that case, the Supreme Court held that section 18(8) does not preclude common law remedies unless the contravention of the statutory requirement is an "essential ingredient" of the cause of action.
Applying this test, the Tribunal found that the contravention of the statutory requirement to report the number of pollution incidents to Ofwat was an "essential ingredient" of the claims. While the Tribunal held that the misleading of a public authority by a dominant undertaking could constitute an abuse of dominance, which is not per se excluded, for the cause of action to be made out, the alleged abusive conduct must cause damage to the claimants. Because the losses claimed arose from the fact that the utilities could charge higher prices under the statutory price control regime because of the underreporting, the statutory contravention was an essential ingredient of the claims.
By contrast, in United Utilities, the Supreme Court found that the losses claimed arose from damage caused by the polluting activity itself and therefore the claim in negligence was not excluded by section 18(8) of the WIA. Similarly, the Tribunal indicated that, had the abusive claims been for losses due to excessive or unfair pricing, they may not have been excluded by section 18(8).
Potential significance of the appeal
Professor Roberts sought permission to appeal to the Tribunal on the following grounds: (i) the Tribunal had misconstrued the claims, which were based on abuse of dominance leading to unfair pricing, not contravention of the WIA price control regime; (ii) the Tribunal had misinterpreted section 18(8) of the WIA in light of the Supreme Court judgment in United Utilities; and (iii) the Tribunal erred in observing that Ofwat's administrative process was better suited to determining the level of underreporting of pollution incidents and any reimbursements due to consumers.
The Tribunal refused permission to appeal, but the Court of Appeal subsequently agreed to hear the appeal. If Professor Roberts' appeal is successful and the Court of Appeal finds that the claims are not excluded by section 18(8) of the WIA, this will have significant implications not only for the water services industry, but also for other regulated entities subject to similar regulatory regimes with reporting obligations relating to price.
