Southern Water could be slapped with a £54 million penalty after its plans for future improvements were branded “inadequate” by a water regulator. Ofwat said the water company’s business plan for 2025 to 2030 did not meet “minimum expectations” and it will impose the hefty fine if proposals are not improved by the end of the year. Ofwat, which is responsible for economic regulation of the privatised water and sewerage industry, said in its draft determination, published nine months after Southern Water submitted its plans, that the company’s performance “lags behind” others in the sector.

Key expectations set out by Ofwat to be achieved between 2025 and 2030 include Southern Water delivering a 35 per cent reduction in storm overflow spills, supported by a £622 million programme of investment, delivering a 13 per cent reduction in leakage and helping customers reduce their water use by two per cent. Ofwat also expects the company to invest £76 million in metering, including rolling out smart meters. Read more: Water boss pocketed £700k last year as customers prepare for bill price hike It proposed Southern Water reduce interruptions to customers' water supply by 86 per cent based on its current 2020-23 performance.

And the company is also expected to reduce incidences of internal sewer flooding by 13 per cent as well as invest £89 million to improve drinking water quality. “In 2022-23, Southern Water performed better or at the required level of performan.