Profits at Thames Water have plunged 60% after regulatory penalties and extreme weather hit the group.

Pre-tax profits fell from £129 million last year to £67.7 million in the six months to the end of this September.

The private utility company said that the summer heatwave combined with the “beast from the east” in spring delayed ability to fix leaks.

Following the failure to tackle leaks, Thames Water was fined £120 million by the regulator Ofwat. Of this penalty, £65 million was paid back to customers.

During the same period, Thames Water received 11,000 written complaints about supply interruptions. In the same period last year, the group received 8,000 complaints.

“During the intense summer heatwave we worked tirelessly to protect our customers from supply restrictions,” said chief executive Steve Robertson.

“However, along with the impact of the ‘Beast from the East’, it has delayed our progress on leakage and other performance measures. We remain focused on building a better future for our customers and the environment.”

“Our profit decreased over the period as we brought forward regulatory penalties, to benefit customers, and hired more employees to improve customer service and tackle leakage. Our capital investment increased, with £554 million spent on improving our water and waste networks.”

“Our long-term investors are committed to the high investment levels required to face the challenges created by climate change and population growth, and continue to not take any dividends. Our record £11.7 billion business plan for 2020-25 will help to further transform our infrastructure and customer service, as well as provide the necessary extra support for people in vulnerable circumstances,” he added.

Last year, the group was fined £20.3 million after untreated water was found to be leaking onto land and killing wildlife.