Thames Water was fined £160,000 at Stratford Magistrates’ Court today (10 June) for water quality offences which occurred at Coppermills water treatment works in Walthamstow, London in 2017.

Additional costs of £79,839.68 were agreed and a victims’ surcharge of £120.00 was applied.

The fine was in respect of three offences arising from two events in February and July 2017 when there were failures in the disinfection of drinking water at the treatment works.

Charges were bought by the Drinking Water Inspectorate (DWI), which confirmed no consumers were harmed by the events.

However, it claims that Thames Water has experienced “a number of similar incidents” at other works.

The water company has apologised and said it has incorporated the lessons into the way it operates its business.

The DWI said that while no consumers were affected by the events they were put at risk as disinfection of drinking water is a “key public health measure”.

Marcus Rink, chief inspector of drinking water said: “Whilst these events did not result in impact or harm to any consumers, Coppermills water treatment works suffered loss of control of key treatment processes on two occasions in 2017.

“Thames Water have experienced a number of similar incidents at other works which have led to repeated recommendations since 2014.

“Recommendations on training, procedures and maintenance must be acted upon to reduce current and future risks. It is undoubtedly in the public interest to bring this prosecution for a strategic works which contributes to the supply of over two million consumers in Greater London.”

The DWI said that in the first event, errors occurring in “poorly planned” electrical maintenance at the works led to the loss of control of the disinfection system and inadequately disinfected water entered supply.

While in the second event disturbance in the flow of water across a sand filter raised turbidity (cloudiness) of the water and this affected the subsequent disinfection process.

A spokesperson for Thames Water said: “We take our responsibility to produce and supply high-quality drinking water incredibly seriously, and we’re really sorry that we fell short on this rare occasion. There was no harm to public health, and we’ve used the regrettable experience to learn many lessons which we’re already incorporating across the business.

“Our teams work hard around-the-clock to provide an essential service to our customers, who are our top priority. As part of our latest business plan, we’ve pledged to invest record amounts in our assets to improve service and keep taps flowing with the high-quality drinking water our customers rightly expect.”

Thames Water is “transforming” its water treatment processes to meet stringent new regulations.

This includes a £42 million upgrade of the Coppermills site, which is currently under construction, to increase its resilience amid “rapid population growth and climate change”.

The water company is also working with the DWI on a “detailed action plan” to reduce the risk of similar incidents occurring in the future.

Thames said teams at Coppermills “quickly identified” the breaches, which happened in February and July 2017, and were due to manual handling errors relating to chlorine dosage levels and the flow out of the site.

It said no untreated water entered the public water supply at “any time”.

Coppermills water treatment works is the sole supply to 728,000 consumers but contributes to two million consumers’ water supplies across the London area.

Thames Water is on the hunt for a new chief executive after Steve Robertson stepped down suddenly at the end of last month. Ian Marchant, who has been independent chair since January 2018, became interim executive chair and will remain in that role until a new CEO is appointed.

Robertson will remain an employee until 30 June to “ensure an orderly transition” working with Marchant.

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