Householders woke to no running water and two schools had to close after a burst water main affected a vast area from St Agnes to the Roseland, including the city of Truro, last Tuesday.

The incident occurred as the Environment Agency named South West Water “the worst performing company for pollution incidents in the Environmental Performance Assessment’s 13-year history”.

Threemilestone School and St Agnes Academy closed for the day, and problems were reported as widely as Carnon Downs.

South West Water confirmed that it was “working hard” to repair a burst on a large mains supplying postcodes in the TR area, with customers experiencing “low water pressure or a temporary loss of supply”.

The network was “revalved” and supply began to return at around 2.45pm. However, customers were advised to run their taps for up to an hour to fix discolouration caused by “natural sediments”, and to apply for “run-off allowance” compensation.

A South West Water spokesman said the company was “very sorry for the disruption caused”.

Truro and Falmouth MP Jayne Kirkham said she would be making sure South West Water compensated affected customers.

“Our water bills in Cornwall are amongst the highest in the country yet, as this incident appears to indicate, investment has not been sufficiently made in the infrastructure,” she said.

“Vulnerable people and hospitals should not be losing access to clean water, and regular sewage spills should not be happening on our beautiful Cornish beaches.”

On the same day, South West Water was one of five water companies given a two-star rating by the Environment Agency, meaning it requires improvement.

It was fined over £2m last year, and scored red for total pollution incidents for the 13th year running, with 194 pollution incidents in total. It also performed significantly below target for discharge permit compliance with 12 failing sites, the worst of all companies. 

Clarissa Newell, Environment Manager for Devon, Cornwall and Isles of Scilly, described South West Water’s environmental performance in 2023 as “really disappointing”.

“Consistently poor performance is not tolerated,” she said. “With an increase in dedicated staff to regulate water companies and a quadrupling of site inspections, companies failing to comply with the law will be penalised.”   

A South West Water spokesperson responded: “Delivering improvements in our environmental performance remains our top priority.

“Our 2023 EPA performance maintains many of the important improvements we delivered last year, including no serious Category 1 pollutions.

“Nevertheless, we recognise that further improvement is required. We have always been clear: one pollution is one too many.”

The spokesperson promised “a doubling in investment over the next five years” to deliver long-term resilience, affordability and environmental protection in the face of “rapidly changing climate and evolving weather patterns”.