Cost of tackling storm overflow spills rises to £60bn

The forecasted cost of tackling discharges from storm overflows has been raised to £60 billion, up from the £56 billion figure calculated in 2022.

This will add an estimated £70 to customer bills by the middle of the century to pay for proposed improvements, according to cost analysis by the Department for Environment, Food and Rural Affairs (Defra).

The cost hike is a direct result of government expanding the remit of the Storm overflow discharge reduction plan to cover all marine and estuarine waters. It follows feedback that the original plan did not offer adequate protections to coastal waters.

Responses to the consultation on the original plan, which was published earlier this year, included concerns that marine protected areas and shellfish waters should be added to the list of high priority sites. This was done to drive faster action in these areas to meet the targets.

Under the updated plan, which will be reviewed in 2027, the targets will cover all storm overflows – an increase from 91% coverage of the original plan.

Environment secretary Therese Coffey said “no overflow will be left behind” under the requirements of the plan. “Through more investment, stronger regulation and tougher enforcement of the water sector we will tackle pollution from every storm overflow in the country.”

The requirements for water companies by 2035 to improve all overflows close to bathing waters and for 75% that discharge near high priority sites remain the same. All storm overflows, regardless of location must be addressed by 2050.

An overwhelming majority of respondents (98%) supported the idea of a developing an ecological standard for coastal and estuarine water, but recognised the complexities such work would entail.

This is anticipated to add £4 billion to the costs due to the extension of the rainfall target to coastal and estuarine storm overflows.

Costs to each water company will be proportionate to the number of overflows in each region’s network.

The highest density of overflow points are in areas where sewer systems were built during industrial development, such as much of Yorkshire and the north west, when combined sewers were commonplace.

Cost modelling published by Defra suggests United Utilities will bear 35% of the costs and Yorkshire 27% with Anglian anticipated to shell out just 1% of the capital cost due to fewer overflows in its area.

A legal challenge was mounted against Defra for its original plan for not including coastal waters and estuaries.

By the end of 2023 all water companies will be required to fit monitoring equipment to their combined sewer overflows to allow monitoring that provides data on the potential harm from any spills into waterways.