Wessex Water has highlighted groundwater as the source of dry weather discharges following a report by the BBC yesterday identifying the company, together with Thames Water and Southern Water, as companies that release ‘sewage’ into rivers on occasions when it hasn’t rained.

The water company issued a statement yesterday saying:

“The focus is on these three companies because other companies refused to provide information, while much of the information we supplied has not been included in the BBC reporting.

“The discharges referenced are caused by high groundwater which, unlike rainfall that stops relatively quickly, continues for days or even months. None of these overflows cause rivers to fail to meet ecological standards.”

With regard to issues specific to Wessex Water raised by the investigation, the statement says that out of the eight Wessex Water sites identified by the BBC, there were no discharges at five of the sites.

Groundwater enters the sewerage network largely through private pipes

According to the utility, there are three sites that do discharge when groundwater levels are high when the groundwater enters the sewerage network largely through private pipes.

High groundwater levels infiltrate the sewerage network resulting in excessive flows in the same way as heavy rain, but unlike rainfall that stops relatively quickly the groundwater can continue for days or even months.

Wessex Water has been relining its pipes – however, much of the infiltration is from private pipes that then connect to the public network. The water companies have no powers to require these pipes to be fixed and the resulting discharge is groundwater with a small amount of sewage.

The statement says the company is progressively using nature-based solutions to treat the groundwater and that by 2025 it will have completed, or will be in the process of constructing, nature based solutions to treat groundwater at 28 locations across its region.

Plans to significantly increase investment between 2025-30

Wessex Water is currently investing £3 million a month to reduce overflows, and has plans to significantly increase this level of investment between 2025 and 2030, subject to regulatory approval by Ofwat.

Ruth Barden, Director of Environmental Solutions, said:

“This a known issue caused by high groundwater which, unlike rainfall that stops relatively quickly, continues for days or even months. None of these overflows cause rivers to fail to meet ecological standards."

“We’re using nature-based solutions to treat groundwater affected sites, and by 2025 we will have completed or progressed 28 schemes in our region."

“Meanwhile we’re investing £3m a month on reducing overflows, which we agree aren’t fit for the 21st century, and we’re planning to invest significantly more between 2025 and 2030 subject to regulatory approval.”

Labour’s new shadow environment secretary Steve Reed and Liberal Democrat MP Tim Farron have both separately called for immediate action by the Government.

Steve Reed said there must be an immediate investigation into both the breach of the licence and the environmental damage caused, while Tim Farron described the revelations as “scandalous”, urging the Government to act immediately.