UK water sector faces regulatory reset after South East Water failures

New oversight powers proposed after technical failures and criticism of industry accountability

WATER regulation in England and Wales is set for an overhaul, with a government white paper proposing stronger powers for regulators and the creation of a new chief engineer role.

The plans follow years of public concern over pollution, rising water bills and more frequent supply outages across the privatised sector. The latest controversy came at South East Water (SEW), where 25,000 Tunbridge Wells homes went two weeks without reliable water supply in December. Around 6,500 of these homes suffered a further week-long disruption in January, while 4,500 homes in rural areas around Maidstone relied on bottled water stations. At the time of writing, there are no reported supply issues.

The regulatory changes will merge the four water regulators in England and Wales into a single body with greater powers to conduct technical inspections and issue financial penalties. Marcus Rink, head of the Drinking Water Inspectorate (DWI) welcomed the reforms having previously expressed frustration at weaknesses in existing regulation. At a parliamentary committee hearing into the December SEW outage that left 24,000 customers without supply for more than two weeks – including two hospitals, 15 schools, 19 care homes, 29 nurseries and a kidney treatment centre – Rink said there he did not believe there was a “potential pathway under current legislation” that allowed the DWI to sanction the company. He was therefore speaking “more openly” than usual.

Technical failures at Pembury

The December outage was caused by Pembury treatment works failing to treat the raw water to required standards. Rink told the committee that SEW’s Pembury treatment works had been operating “sub-optimally” for months. Subsequent supply issues were not linked to treatment failures but Rink warned the plant remained at risk.

Rink told the committee the Pembury failure “should not have been a surprise”. Pembury was placed under an improvement programme in October 2024, following a September alert from SEW citing water quality risks including E. coli and pesticides.

Rink told the hearing that DWI process scientists have since found “clear evidence” of poor filter performance and “inadequate” coagulation management – an early stage in treatment where chemical additives aggregate suspended solids.

Rink said that SEW was effectively “flying blind” because the works lacked electronic monitoring of coagulation, meaning operators could not respond to changes in water flow that affect coagulant concentration.

The DWI found that rather than stimulating coagulation, aluminium from the coagulant was forming a solution and being caught in the granular activated carbon filters. It was then removed from the filters during backwashing, causing the washwater tank to fill more quickly and reducing the effectiveness of subsequent washes. Ultimately, treated water fell below quality standards and supply was cut between late November and mid-December.

In the same hearing, CEO David Hinton blamed the failure on changes in water pH and alkalinity, rendering their existing coagulant ineffective, arguing that the problem was not “foreseeable”. Hinton said he believed the chemistry changed due to reduced groundwater levels and said supply was stretched by more people working from home since Covid. However, this was refuted by Rink who said there was “nothing unusual” about the water chemistry.  

This contradiction prompted committee chair Alistair Carmichael to write to both Hinton and SEW chair Chris Train, asking them to address Rink’s testimony. After Train submitted a response that corroborated Hinton’s evidence, Carmichael recalled both executives to parliament to address “significant concerns about the evidence”.

In a letter to Train, Carmichael said: “My colleagues and I remain deeply sceptical about the company’s version of events to date, and its board’s track record of holding the company to account”.

Train promised a “rapid in-depth review” led by a non-executive director and supported by a senior SEW director. Carmichael accused the company of attempting to “mark their own homework” and to “buy themselves time, to hunker down until this storm blows over”.