Liv Garfield, CEO of Severn Trent, is set to step down after an 11-year tenure that saw her become the FTSE 100's longest-serving female leader.

The utilities group, which delivers water and sewage services to over 4.7 million homes and businesses across the Midlands and Wales, announced that Ms Garfield will depart at the end of December.

Her successor will be James Jesic, currently serving as capital and commercial services director at Severn Trent and managing director of Hafren Dyfrdwy Cyfyngedig in north east and mid-Wales.

Ms Garfield will remain with the company until the end of March next year to ensure a smooth transition.

Currently, she holds the record as the longest-serving female boss on London's blue-chip share index, followed by GSK CEO Dame Emma Walmsley, who has led the pharmaceutical giant for eight years.

Dame Emma is also due to leave GSK at the end of this year, with chief commercial officer Luke Miels set to take her place, reducing the number of FTSE 100 female leaders to 10.

Russ Mould, investment director at AJ Bell, said: "Those two are also the longest-serving female bosses in the index, and their departure will take the average tenure for a FTSE 100 female leader down to 2.8 years from four, compared to the index-wide average of 6.1 years."

The announcement of Ms Garfield's departure coincided with half-year results showing a 60% surge in pre-tax profits to £307.8m for the six months ending September 30.

The company has also raised its annual forecast, now anticipating performance incentives of at least £40m, up from previous guidance of at least £25m. This improvement is attributed to strong results in reducing leakage, storm overflow spills and pollution incidents.

Severn Trent is simultaneously reducing costs whilst boosting its infrastructure renewals expenditure.

The figures come after the firm increased bills by an average of 21% in April, representing approximately a £99 annual rise, bringing the average household payment to £556 over the year.

Severn Trent stated at the time that the substantial bill increase would help finance around £15bn in investment to modernise its network of pipes, sewers and reservoirs over the coming five years.

Ms Garfield said: "It has been a true privilege to be the chief executive for the last 11 years.

"I am proud that together we have become widely recognised as a sector leader and now have our largest ever investment programme ahead of us."

Christine Hodgson, chairwoman of Severn Trent, described successor Mr Jesic as a "home-grown leader who has already played a significant role in the success to date of Severn Trent".

"His operational expertise and performance focus, along with his passion for our people, purpose and region, make him the ideal person to lead Severn Trent into our next phase," she said. His starting annual salary will be £775,000, compared to the current £873,200 that Ms Garfield earns before benefits and bonuses.

Mr Jesic joined Severn Trent as a graduate in 2003 and has since worked across the "full breadth of the business", the company stated.

Water companies have been facing increasing public anger over rising bills, high levels of sewage pollution, and executive bonuses in recent years.

Severn is among the better performing privatised water companies on environmental metrics in recent years and exceeded recent targets set by Ofwat, the watchdog reported in October last year.

Severn anticipates halving storm overflow spills to around 13 in 2025 and is on course to meet its leakage reduction target for the eighth consecutive year.

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