Fringe Box



Thames Water Among Worst in the Country – Environment Agency

Published on: 17 Jul, 2023
Updated on: 18 Jul, 2023

Thames Water provide Guildford’s water supply and sewage treatment.

Chris Caulfield

local democracy reporter

Standout levels of pollution and poor monitoring has left Thames Water, which provides water and sewage treatment works for Guildford, languishing joint last among the country’s “very disappointing” water and sewerage companies.

The damning verdict was delivered in a report by the Environment Agency which measured the performance of the nine companies operating in England.

See: Thames Water in Urgent Funding Talks to Avoid Collapse – How Is Guildford Affected?

It found that there were 2,026 “pollution incidents” from sewerage and water supply – up from 1,883 in 2021 leading to the EA’s chair, Alan Lovell to describe the situation as “simply unacceptable”.

Worse, he said, was that early unconfirmed data for 2023 suggests there has been no improvement this year either.

Slyfield sewage treatment works showing the array of tanks and treatments for Guildford’s sewage. Image Thames Water.

The report, published July 12, found that for serious pollution incidents four companies performed significantly below target  – and none more so than Anglian Water and Thames water.

In total there were 44 serious incidents – and 38 per cent of those were from Thames Water alone –  its worst performance since 2013. Of the six worst polluting incidents, half were from Thames Water.

Thames Water’s former CEO Sarah bentley announced her resignation on Jun 28 after criticism of her £1.6m pay packet and the company’s environmental performance. She was in post less than three years.

In Guildford, the number of incidents has been improving with a reduction of untreated sewage discharges sewer into the River Wey at Slyfield from 27 times for 346 hours in 2020 to 11 times for a total of 98 hours in 2021 and seven times for a total of 68 hours in 2022 and only once this year (2023) so far. The live record of Thames Water sewage discharges can be found here (

Thames Water serves around 15 million customers with water supply and sewage treatment including Guildford. Guardian graphic sourced from Ofwat and Thames Water.

The beleaguered utility company, which has faced calls to be renationalised in recent weeks, also led the way in the number of category 3 incidents that caused minor impacts to air, with four.

Of planned environmental improvement schemes, 99.5 per cent were completed as part of the Water Industry National Environment Programme however three companies failed to meet all requirements and Thames Water, with its red rating, performed the worst.

In 2019, regulators Ofwat set the prices water companies could charge and developed environmental programmes for each firm to follow. Thames Water was the only one to have performed “significantly below target” due to 12 water-quality schemes not meeting requirements within planned deadlines.

The EA also expects water companies to report pollution to the body first as “without a rapid response, the impact of pollution can escalate and the opportunity for mitigation measures can be lost.”

The report said that Thames Water was one of four companies to fall below this target, the others being Anglian Water, South West Water, and Yorkshire.

According to the EA, water companies must also install monitoring devices on their storm overflows to capture how often and how long they are used. Thames Water again came last among the utility companies with 61.8 per cent coverage compared with market leader Severn Trent Water which had 99.6 per cent coverage.

Thames Water scored well for satisfactory sludge use and disposal, as well as for its compliance with permits to discharge treated wastewater.

See also: Thames Water Says Sewage Spills ‘Totally Unacceptable’ But Admits Residents Will Pay

Concluding, the report read: “The sector as a whole needs to improve in order to achieve and sustain expected levels of regulatory and environmental performance.

“The majority of water companies are not meeting basic environmental requirements.

“Although we have acknowledged some improvements, these results cannot be taken in isolation.

“They are set against the backdrop of poor and inconsistent results over recent years.

“We are concerned that some companies will not or cannot change. Anglian Water and Thames Water repeatedly dominate serious incident numbers.

It added: “These water companies in particular need to make radical changes now, but all water companies have areas to improve.”

A spokesperson for Thames Water said: “Protecting the environment is fundamental to what we do and we recognise our performance in preventing pollution is still not good enough.

“We’re committed to turning this around and our shareholders have approved additional funding into the business so we can improve outcomes for customers, leakage and river health.

“Alongside implementing our pollution reduction plan to deliver these changes, we have plans to upgrade over 250 of our sewage treatment works and are striving every day to reduce the discharge of untreated sewage into our rivers.

“This is a key part of our River Health Action Plan to radically improve our position in order to protect and improve the environment, as we strive to eliminate all incidents in the future.”

The company has also announced that shareholders agreed to provide an additional £750m to “further improve operational performance and financial resilience”.

Water companies and their rankings (out of four stars).

Water company 2021 (year 1) 2022 (year 2) 2023 (year 3) 2024 (year 4) 2025 (year 5) Total (out of 8 stars)
Severn Trent Water 4 stars 4 stars no data no data no data 8 stars
Northumbrian Water 4 stars 3 stars no data no data no data 7 stars
United Utilities 4 stars 3 stars no data no data no data 7 stars
Yorkshire Water 2 stars 3 stars no data no data no data 5 stars
Anglian Water 2 stars 2 stars no data no data no data 4 stars
Thames Water 2 stars 2 stars no data no data no data 4 stars
Wessex Water 2 stars 2 stars no data no data no data 4 stars
Southern Water 1 star 2 stars no data no data no data 3 stars
South West Water 1 star 2 stars


Share This Post

Responses to Thames Water Among Worst in the Country – Environment Agency

  1. Jim Allen Reply

    July 17, 2023 at 11:27 pm

    Currently the moorefields sewage treatment plant is between 10 and 12% under capacity. It has been out of capacity since 2017 when its treatement capacity first failed to meet demand.

    The new Sewage treatment plant is ocer a year behind so 2027 at the earliest!

    Not to worry though the ‘night soil boys’ have return and are tankering out 4,000 gallons at a time to chertsey, and they are backing up the gravity sewers so expect more road collapse like stoke road.

  2. Andy Clapham Reply

    July 18, 2023 at 10:55 pm

    This massive improvement with only one discharge this year would be a good step forward if it were credible. Anyone who observes and smells from across the navigation will have doubts.

Leave a Comment

Please see our comments policy. All comments are moderated and may take time to appear.

Your email address will not be published. Required fields are marked *