South East Water CEO David Hinton has told a House of Commons Committee that "lifestyle changes and extreme weather events" had contributed to recent water shortages in Tunbridge Wells.

 The water company chief, together with Tanya Sephton, Customer Services Director, was appearing before the House of Commons Environment, Food and Rural Affairs (EFRA) Commitee alongside Marcus RInk, Chief Inspector of the Drinking Water Inspectorate (DWI) in a live evidence session yesterday as part of its ongoing inquiry into reforming the water sector.

About 24,000 households in Kent were left without drinking water for 14 days due to failures at the Pembury water treatment centre - the single source of supply for the Kent spa town. South East Water told residents in Tunbridge Wells and surrounding villages on 29 November that water from their taps was unsuitable for drinking, bathing, giving to pets or brushing teeth - the safety notice remained in place until 12 December.

Hinton was invited to attend the evidence session by Committee Chair Alistair Carmichael MP as the incident unfolded. The DWI, which launched an ongoing investigation on 4 December, had previously warned South East Water in 2024 of a significant risk of failure at the Pembury treatment centre.

"Lifestyle changes and extreme weather events" two main causes

David Hinton told the Committee:

“The resilience issues, and what has been facing us and what has impacted the customers, really started in 2021. We had an uptick in demand following covid. We are a commuter-based area, and a lot of our customers are spending a lot more time at home and there were lifestyle changes. We also had some really extreme weather events over that period, between 2021 and 2025. That has meant that the resilience of these particular areas has been stretched….

“None of the events that have impacted our customers since 2021 has been asset failure-related. They have been where we have been unable to meet demand with our supply. That kick-up in demand and the kick-up in the company you did not see it as foreseeable.extreme weather events that we have seen have been stretching our resilience. That has impacted our ability to deliver the service that we really want to deliver.”

Responding to the comment by Committee Chair Alistair Carmichael that “it sounds like you are not really in control of your own business”, the water company CEO explained that the lack of standards had meant SEW had “been unable to effectively drive and convince the regulator” of the investment that was needed. This had has meant that the company ran “far too close in terms of what we have in infrastructure.”

Incident “fundamentally down to the fact that we have a single source of supply for Tunbridge Wells"

Acknowledging the Chair’s point that the incident was not extreme weather-related, Hinton said it was “fundamentally down to the fact that we have a single source of supply for Tunbridge Wells.”

Asked whether the company did not “see the incident as foreseeable” following a warning 12 months ago by the DWI about the treatment plant, he told the Comittee that a change in the raw water chemistry not seen in 20 years had caused the event, saying:

“It was not a failure of the asset; it was not a failure of the treatment works per se. It was a change in the water chemistry.”

He explained that the coagulation chemical used in the treatment process for 20 years had “stopped performing as it should” which meant disinfection could potentially be compromised.

“Initially, we did not know that that was the issue; we thought it was the coagulant we were using…

It was an unexpected failure of the coagulant process, which we did not initially nail as the issue because the raw water quality had never changed like it had done in this particular event”, he commented.

Alastair Campbell also raised the financial position of South East Water saying that overall, in 2023, it was reported that South East Water spent more on dividends and servicing debt than on infrastructure and investment. David Hinton commented that the article was run by the Financial Times and that as part of a simplification of SEW’s financial structure, a set of moneys had been transferred from one instrument to another.

“In the parlance of finance, that is called a special dividend. So while the headline technically is correct, none of that money left and went to shareholders; none of that money left and went outside the business,” he said, causing the Chair to say:

“If your finances are too complex to be understood by the Financial Times, are they maybe just too complex?”

Running with a single coagulant "In hindsight, that is something that we will not do at this site or any others like it.”

David Hinton went on to face detailed questioning on the Tunbridge Wells event. In terms of the previous risk notice issued by the DWI, asked by Charlie Dewhirst MP whether in hindsight, was there something that could have been done sooner to improve the Pembury site to avoid this incident, the water company boss replied:

“Absolutely—in hindsight the water chemistry at Pembury is groundwater and it is normally very constant, but it changed. We had never seen that in 20 years. In hindsight, I wish we had had the alternative coagulant on site. We tried loads of different chemicals to see if they worked. Those are all used across the industry, and we took industry advice about this really unusual thing that was happening.

“We took expert advice from process scientists all over the country and everything was pointing to changing the coagulant, which we did over a number of days to try and get it to work. Now, if we had had the alternative on site—which we now do—we could have just flipped it and there would be no impact on customers at all, but we were running with a single coagulant. In hindsight, that is something that we will not do at this site or any others like it.”

DWI Chief “Yesterday, I spent a good hour listening to what my inspectors were saying about South East Water, and what their expert opinion was about that incident - it was grim listening.”

Appearing before the Committee after David Hinton had been questioned, commenting on the outage, DWI Chief Marcus Rink said:

“For someone who has worked for decades in the water industry and as a regulator for more than two decades, I was seriously disappointed. It is a real shame that this has occurred. It leaves a black mark on the water industry.”

He continued:

“The examples that we have heard about this morning were far from excellent, and they followed recommendations in an April 2024 audit of ours that focused on the inadequacy of the preparations of the company following incidents in 2023, 2022 and 2018. In fact, I counted 20 incidents that took place since the beginning of 2022 that were due to loss of supply…

“Yesterday, I spent a good hour listening to what my inspectors were saying about South East Water, and what their expert opinion was about that incident - it was grim listening.”

"They were flying blind...They had no idea"

Responding to the Chair’s comment that Mr Hinton’s evidence was that “this was something extraordinary and unforeseeable”, Marcus Rink went into considerable detail, saying:

“We have identified that Pembury works had been operating sub-optimally for weeks and months prior to the event.

“There is clear evidence of poor filter performance, inadequate coagulation management, reduced backwash capacity, reliance on manual interventions, and a lack of online performance visibility to enable a critical assessment and response. They were flying blind. There was no electronic collection of data on coagulation. It was fixed manual dosing, which meant that if the flow of water changed, the dosing remained the same and the concentration changed.

“The DAF filters were not washed adequately. The backwash system had a passing valve into the dirty wash water tank. From January, the site was shutting down, following a GAC wash. As I have said, the chemical dosing was not visible on SCADA. The lack of online data for coagulant flow and dose means that there was no way for the site operators to notice or intervene in coagulant dosing injector blockages, should they occur.

“They had no idea. The process scientists responsible for the site were not available - they were sick - so there was a stand-in scientist working there. The filter performance drops away on DAF filters at various dates. In the opinion of my inspectors, the start of the incident was 9 November.”

Asked by Terry Jermy MP whether he was concerned about the likelihood of the incident being repeated, Marcus Rink replied bluntly: “Yes”, going on to say that the DWI’s report on the incident “will not be pretty reading.”

However, he went on to emphasise that did not mean that all the industry is like that and also did not mean that we do not have a fantastic water industry, commenting:

“We do: we have a lot of people who are working very hard to make it right and to provide good-quality drinking water, and we are-world leading. Let us keep it that way. Let us not allow one of the team to let us down, when we have some fantastic water companies that do their job.”

Click here to download the full transcript of the evidence session.