Sussex water supply outage affected 25,000 properties - Cause revealed

Customers were left with ‘no water’ following a ‘failure’ at one of the company’s supply works in May. The Horsham and Chichester districts were affected.

“An investigation into the reason why customers in areas of Sussex lost their water supply in May 2023 has now concluded,” a Southern Water spokesperson said on Tuesday, August 15.

"Hardham Water Supply Works was automatically shut down late in the evening on Friday, May 12 when sampling highlighted a change in water quality. None of this water entered public supply.”

Southern Water said ‘around 25,000 homes and businesses’ were affected ‘at the peak of the incident’. Supply was restored to 22,500 properties by Monday, May 15. All remaining customers’ supplies were restored a day later.

‘Extensive sampling processes’ look for 160 different substances in water, ‘to ensure water quality is as high as it should be’, the water company said.

Tim McMahon, Southern Water’s water director, said: “We are very sorry to those who were impacted by this disruption. We have carried out a thorough internal review into what happened, as it is vitally important we are transparent with customers when we fall short of expectations.  

“Our investigations found that the water entering Hardham from the nearby river and storage reservoir was unusual in that it contained more sediment and impurities than normal, which caused difficulties for our treatment processes.

“Unfortunately, there is no way of knowing the exact source given the number of potential factors, such as agricultural and industrial run-off, but we have fully reviewed our own on-site policies and procedures so we are as prepared as we can be if this were to happen again.”

A list of actions taken since the incident are included in the findings report.

A spokesperson for Southern Water added: “We have proposed a £63 million spend on improving the resilience of Hardham Water Supply Works after 2025, and are in discussions with regulators to make this happen as quickly as possible.

“We’re also reviewing where we can improve customer experience during water supply incidents and continue to address local water supply and demand challenges.”

Any customer who would like a paper copy of this report can contact Southern Water on [email protected].