Our Annual Performance Report

Here you can view or download our latest Annual Performance Report. It includes both our financial and non-financial performance.

Annual Performance Report

Report overview

This report sets out the performance in 2024–25 of Southern Water’s regulated business, as defined under our Licence (the licence to operate as a water and sewerage undertaker). This is both in financial terms and against our outcome and performance commitments. 

We had 47 performance commitments agreed as part of the price review process from 2020-25. Over the past five years, we’ve seen a significant improvement to our performance, but we didn’t meet all the targets Ofwat set within its Final Determination (the basis on which our plan for 2020–25 was approved).

Statistics from the annual performance report

Despite setbacks in some areas, we've also seen small improvements in performance across a large number of areas over the past year.

47%

Reduced internal sewer flooding by 47%

9%

Reduced in-year leakage by 9%

28%

Increased number of customers on our Priority Services Register by 28%

43%

Unplanned outage has been reduced by 43%

Statistics from the annual performance report

Despite setbacks in some areas, we've also seen small improvements in performance across a large number of areas over the past year.

47%

Reduced internal sewer flooding by 47%

9%

Reduced in-year leakage by 9%

28%

Increased number of customers on our Priority Services Register by 28%

43%

Unplanned outage has been reduced by 43%

We’ve already improved our performance

A reset of our leadership, culture, systems, processes and people, alongside a step change in investment over the past five years, has led to significant improvements in performance, focused in the areas you’ve told us are most important. Read our Annual Report.

Leakage

We've achieved a 10% (in-year) reduction in leakage over the past two years, and are recording close to a 23% drop in weekly recorded leakage levels (from April 2024). This is a result of a targeted proactive programme of work that includes pressure management schemes, compliance checks, customer engagement, root-cause analysis and new detection modelling surveys and tools.

108.5 22-23

107.5 23-24

97.7 24-25

Pollutions

We've invested £23.3 million over the past five years (2020–25), reducing total pollutions by 38%. This investment has helped to improve the reliability of our pumping stations, minimise rising-main bursts and increase the efficiency of our sewer level monitors so that we can proactively prevent incidents from happening. We know the level of serious pollution incidents is still unacceptable and we're focused on addressing the root cause of each incident.

358 22-23

234 23-24

269 24-25

Internal flooding

During 2024–25 we installed a further 8,000 sewer level monitors – bringing the total to around 32,000 added to our network since 2023. Feeding data into our Control Centre, these monitors have helped to reduce the number of flooding incidents experienced by our customers, with teams now able to proactively manage maintenance and repair.

496 22-23

527 23-24

277 24-25

Water quality

Our customers expect us to provide clean, safe drinking water and we must follow strict guidelines issued by the Drinking Water Inspectorate through a compliance risk index score (CRI score). We achieved 3.82 (2023–24: 3.07), a 40% improvement on our score of 6.38 in 2022–23. As part of our turnaround, £150 million has been invested since 2023 to make improvements at five of our largest water supply works; Otterbourne, Testwood, Hardham, Burham and Sandown; with 103 actions and 99% of projects now completed.