Ofwat has published findings from research into a Southern Water supply interruption that took place in Southampton and Marchwood in December 2024 - and is calling on water companies to ensure they can provide alternative water quickly to vulnerable customers.

The interruption began for customers on 18 December and water returned for most by 20 December 2024. Almost 130,000 people (60,000 households) were impacted by this incident.

The regulator commissioned Blue Marble to conduct research with household customers and some non-household customers (such as care homes) to understand more about the customer experience during this supply interruption, including whether people received the support they needed.

The findings raise concerns about the provision of alternative water, particularly to vulnerable customers. Ofwat is emphasising that all water companies must ensure that they are prepared for when something goes wrong and can meet the needs of their customers.

The research included a survey of 500 residents in the affected area and qualitative research with 71 participants. The combined findings highlight a number of issues faced by customers. In particular, there were problems with the provision of alternative water via water deliveries or water stations:

• Water collection stations – customers felt the water collection stations were not successful at providing water throughout the incident. There was dissatisfaction around the number and location of stations, as well as overall management. Around three quarters (74%) of respondents to the survey were dissatisfied with the alternative sources of water provided.
• Water deliveries – Many vulnerable customers on the priority services register did not feel supported by Southern Water. More than half (57%) of priority services customers reported that they did not receive a water delivery, of which four-fifths (82%) were expecting one.

Next steps

Ofwat’s customer-focused licence condition (condition G) requires all companies to have an understanding of the needs of their customers and provide appropriate support, particularly for customers in vulnerable circumstances and during incidents.

Lynn Parker, Senior Director for Casework, Enforcement and Customers said:

“It is vital that companies can provide alternative water quickly to vulnerable customers when a supply interruption occurs. This means understanding the needs of their customers, maintaining and growing their priority services register, having sufficient alternative water in place, and a realistic and effective plan to deliver this water in a timely way.

“Over recent months, we have seen vulnerable customers raise concerns about not receiving water during supply interruptions that have occurred in different water company areas. Often companies will be working towards getting water to these customers, but delivery is too slow or vulnerable customers are missed off the list.

“We want companies to get this right every time.”

Ofwat will be:

• Reviewing the findings from the Southampton and Marchwood incident with Southern Water. This includes considering their plans for future incidents and understanding how the problems faced by customers will be prevented in future.
• Writing to all water companies to make clear that they need to be confident in their ability to effectively respond to a supply interruption, specifically in relation to the services and support that would need to be provided to customers. We expect any areas that need improvement will be acted on quickly.
• Reviewing significant future supply interruptions and taking action if companies fail to provide adequate support to their customers, including vulnerable customers.

Click here to download the report