Speaking at a summit to tackle chalk stream pollution, the chief executive vowed to “do what is right for these rivers”.
“I’m absolutely committed to ensuring we’ll play our part in restoring these iconic water bodies to their former glory,” she said after the meeting three years ago.
But since then, things have not gone as smoothly as she perhaps hoped.
In recent weeks, it has emerged that leaks at Thames Water are at a five-year high and the company is once again on course to miss them in 2023.
Thames was also accused of attempting a “flimsy PR stunt” after Bentley announced she was forgoing an annual bonus, at the same time as a report showed the near-doubling of her pay – to around £1.5m – via other means.
Sarah Bentley, who quit as Thames Water boss on Tuesday, received a reported £2m in 2022 - Thames Water/PA
Thames Water defended the one-off extra payments, insisting they were “unrelated to performance” and part of a separate package agreed when the company hired her.
In the statement, the departing boss said it had been an honour to run the company and claimed to have laid down the foundations of the turnaround she had promised.
But no explanation was given for her shock exit – and she leaves behind a legacy that is half-finished at best.
Thames Water supplies drinking water to 15 million people in London and the Thames Valley and made a profit of £536m in the six months to the end of September.
However, bosses have found themselves personally in the crosshairs over boardroom largesse and huge shareholder payouts.
Bentley, who has been chief executive since September 2020, received a reported £2m in 2022.
The company was heavily criticised under former owners Macquarie for paying out more than £2.7bn in dividends, while taking on over £2.2bn in extra debt.
Macquarie has always maintained it is a responsible investor. The private equity behemoth sold its last holding in the business for a reported £1.3bn in 2017 and later bought rival Southern Water.
Since then, the Thames Water board has sought to attract investors with a longer-term view of things, such as pension funds.
Between 2017 and 2021, the company had accrued another £32m in penalties for 11 other cases of water pollution, according to the Environment Agency.
The water in the company’s namesake river was so polluted at one stage that when David Walliams, the comedian and author, blamed it for causing an illness after a charity swim.
Thames has continued to struggle with overflow discharges during rainy weather even after Bentley’s arrival.
Last year, according to data from the website Top of the Poops, Thames Water discharged sewage overflow 8,014 times – the equivalent of 22 times per day.
The discharges lasted for 74,693 hours – or more than eight years cumulatively – in 378 locations.
Following a mea culpa by the entire industry over failures to tackle sewage problems, Thames has announced plans to invest £1.6bn in its sewage treatment works and sewer networks in a bid to halve discharges by the end of this decade.
It has also pledged action to reduce the risk of future droughts, in which water pumped from rivers will be replaced with “recycled” and treated sewage. More water will also be transported from Wales using pipelines.
The business also found itself in the spotlight again when villagers in Northend, on the border of Oxfordshire and Buckinghamshire, discovered water was no longer coming out of their taps. The problem was blamed on a technical issue at a nearby reservoir and Thames was forced to hand out emergency supplies of bottled water.
The failure to bring leaks down – with around 630 million litres still lost each day, enough to fill 252 Olympic swimming pools – could make it harder for the company’s to win regulatory approval for its drought-busting plans.
The company is also under financial pressure and has been seeking a cash injection of around £1bn from investors in recent months.
Bentley’s abrupt departure on Tuesday is unlikely to make things any easier.
Senior figures at the company will now be scrambling to salvage the situation, with Alastair Cochran and Cathryn Ross appointed as joint chief executives in her wake.
Whatever her reasons, Bentley’s departure has certainly made a splash at Britain’s largest – and perhaps most controversial – water provider.
