Southern Water has secured an additional £300 million of equity funding to support delivery of its £8.5 billion investment programme.

The new capital is provided by a consortium led by Macquarie Asset Management (MAM), alongside Asterion Industrial Partners (AIP), an independent European infrastructure investment manager headquartered in Madrid with approximately $10 billion of assets under management. AIP will provide the majority of the new funding and will become a minority shareholder in the company.

This latest investment completes in full the £1.2 billion equity support package announced in July 2025 and brings total equity invested in Southern Water to £2.8 billion since MAM acquired the business in 2021. No dividends have been paid to shareholders during this period.

Proceeds from the equity raise will back Southern Water's record investment programme for the 2025–2030 regulatory period (AMP8), adding capacity and resilience across infrastructure and services to meet new legislation, higher environmental standards and the impacts of climate change, as well as customer expectations.

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In the first year of AMP8 (the year ended 31 March 2026), Southern Water said it continued to make progress with its operational turnaround, delivering improvements in water supply interruptions, leakage and external sewer flooding, alongside a record level of capital investment in its network. The company said it remains focused on areas requiring further improvement, particularly reducing serious pollution incidents.

Lawrence Gosden, Chief Executive Officer of Southern Water, said: "Over the past four years, we've worked hard to transform Southern Water, improving operational performance while significantly increasing investment in the services and infrastructure our customers rely on every day. We're seeing the benefits of that progress, but we remain focused on the substantial work still ahead.

"This additional equity support enables us to build on that momentum as we deliver our ambitious £8.5 billion investment programme over the next five years. It'll help us improve services for customers, strengthen the resilience of our infrastructure and continue reducing our environmental impact.

"We're grateful for the continued support of Macquarie, whose long-term investment and industrial expertise have been instrumental in supporting our turnaround. We're also pleased to welcome Asterion Industrial Partners as a new shareholder. Their investment represents a strong endorsement of the progress we've made and confidence in our plans for the future. We look forward to working with them as we continue delivering for customers, communities and the environment."