South West Water was fined £1,853,000 – a record fine for a drinking water offence – at Exeter Magistrates' Court, following a prosecution brought by the Drinking Water Inspectorate (DWI) for drinking water failures that led to a Cryptosporidium outbreak in the Brixham area of Devon.

In addition to the fine, a victim surcharge of £2,000 was imposed, and South West Water was ordered to pay prosecution costs of £75,000. South West Water pleaded guilty to the criminal offence of supplying water unfit for human consumption under the Water Industry Act 1991, and had faced an unlimited fine.

The incident: Cryptosporidium outbreak in Brixham

Between 15 May and 8 July 2024, up to 39,000 consumers were subject to a boil water notice following the detection of Cryptosporidium in the drinking water supply. Over 390 customer contacts reporting illness were received by South West Water during the incident.

The DWI's investigation found that Cryptosporidium from animal faeces entered the drinking water supply network on agricultural land, likely via an exposed and faulty air valve covered in mud. Soil samples taken in the vicinity of the air valve contained Cryptosporidium oocysts whose DNA matched the Brixham strain of the illness.

The prosecution also told the court that air valves South West Water had in place "were not being inspected in accordance with the policy [South West Water] drafted in 2020", and that the farm had never been inspected, despite being described as a "high-risk site". The risks around air valves were said to have been known for more than 10 years, and the DWI had recommended companies have formal inspection policies four years before the outbreak – but not a single air valve was inspected.

The prosecutor said 537 people became ill, of whom 159 had contact with the healthcare system and 10 were admitted to hospital. People suffered diarrhoea, stomach cramps, dizziness and sickness. Schools, businesses and the local economy were all affected, with school attendance and GCSE results impacted, particularly for disadvantaged children.

At one point during the crisis, South West Water wrongly lifted its instruction for 28 houses to boil water because of "issues with its digital mapping system."

The Court's findings

Judge Smith said: "This was a serious failure by South West Water. The harm caused was wide-ranging, multilayered and profound." The judge noted that water companies were "regional monopolies" with "captive customers", and that the outbreak had led to an enduring mistrust of the local tap water.

The court heard that South West Water has had 22 convictions since June 2014, including supplying water unfit for human consumption in north Devon in 2018.

South West Water's response

Dominic Kay KC, for South West Water, said the company unreservedly apologised and felt genuine remorse. He said South West Water had created a policy on air valve inspection following the DWI recommendation, but accepted it had not been implemented.

David Harris, the managing director of water services, said: "We have cooperated fully with the Drinking Water Inspectorate throughout its investigations and through the end of the legal process. We apologise again to our customers who were impacted and have always taken full responsibility for the water that was supplied."

Remediation steps taken

Following the incident, South West Water carried out extensive work to make the water supply safe. This included flushing the network and a specialist deep-clean of the water mains, as well as installing permanent ultraviolet disinfection and fine filtration systems at the two service reservoirs supplying the Brixham area – safeguards that remain in place today.

The DWI also carried out an industry-wide review of how to inspect and maintain air valves across networks, and issued South West Water with a formal legal notice requiring improvements to its air valve risk management.

Regulatory significance

Marcus Rink, Chief Inspector of the DWI, said: "It is right that South West Water pleaded guilty to this offence and has been held accountable. Today's outcome demonstrates that when failings occur, there will be serious consequences."

This case is the first prosecution under section 70 of the Water Industry Act 1991 involving Cryptosporidium with confirmed consumer illness in over a decade.

Next steps for water industry infrastructure

This case is directly relevant to clients who have just taken on programme delivery partner responsibilities across the water industry’s 15-year investment programme. The South West Water case illustrates the regulatory and reputational consequences of infrastructure maintenance failures in the water sector, and reinforces why the nation's water capital investment programme (which some of our clients are central to delivering) is commercially and regulatorily critical.

It is also a useful prompt for discussing how the contractual scope of our client’s programme delivery role is defined, and what its liability exposure would be in the event of an infrastructure failure linked to a project it is delivering. To further discuss the topics raised in this article, please contact our specialist energy and infrastructure team.