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  • by Karma Loveday

Storm Overflow Plan net cost at near £40bn

The new Storm Overflow Discharge Reduction Plan is estimated to have a net value cost of nearly £40bn.

Defra has published the impact assessment for its sewage pollution clean-up plan. This showed best estimates (which it accepts are uncertain) with costs at £42,873m and benefits totalling £3,276m with a negative net benefit (present value) at -£39,596m

In its Storm overflows discharge reduction plan: Impact assessment Defra reported the cost and benefit breakdown as follows.


This covers capital investment in equipment to contain and treat storm overflows (range in PV terms base year 2022: £25,805m to £40,746m); associated operating costs (£716m); and the cost of financing the investment (£10,023m to £15,827m). The direct impact of these costs will fall on the nine regulated sewerage companies in England, but would be passed to customers in their bills. Defra said the costs of embedded carbon (£627 to £1893m) had been treated as costs to the general public rather than costs to business. The costs assume an evenly phased programme from 2025 to 2050 and adequate supply chain capacity.


Defra explained the monetised benefits fall into three groups: ecological (range in PV terms base year 2022: £471m to £678m), public health (£694m to £998m) and social, reflecting the degree of societal concern with the discharge of raw sewage to the environment (£2,193m to 2,397m). The impact assessment noted: “The benefits affect the whole population but particularly those who make recreational use of affected waters or have an interest in or concern for the ecology of the water environment and water-dependent ecosystems.”


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