The water watchdog has launched an investigation into South East Water over its service to households after “too many customers have been failed too often” by the supplier.
It comes after the firm imposed a hosepipe ban earlier this year, blaming more people working from home for ramping up demand and “testing” its infrastructure.
South East Water is currently the worst performer for water supply interruptions in England and Wales, Ofwat said.
It serves about 2.2 million households and businesses in Surrey, Kent, Sussex, Hampshire and Berkshire.
Over 2022-23 an average of more than three hours of supply was lost per property, compared with the company’s performance commitment level of about five minutes and 45 seconds, according to the regulator.
The firm was summoned to an urgent meeting in June after imposing its hosepipe ban, when it was flagged that its supply resilience was below what is expected.
A spell of hot weather led thousands of properties to experience interruptions, low pressure, or have their supply cut off during the summer, with some schools forced to close.
Ofwat chief executive David Black said: “Providing reliable water supplies is at the heart of a water company’s responsibilities.
“Too many customers have been failed too often by South East Water.
“That’s why we are now carrying out a thorough investigation into the company and its service to customers.
“We are clear that water companies must do more to regain public trust and it must start with better service.
“Where this does not happen, we will use all of our powers to ensure the sector delivers better value for both customers and the environment.”
The Consumer Council for Water (CCW) said it is supporting Ofwat’s investigation because customers’ trust in the supplier has been “undermined by the company’s repeated poor handling of supply interruptions”.
Chief executive Mike Keil said: “There was considerable anger and frustration among many people who felt unsupported, compounded by the company’s poor communication.
“Customers have a right to expect better from an essential service provider.”
A spokesperson for South East Water said: “Resilience forms a major focus for South East Water both now, and as a significant part of our PR24 (2024 price review) business plan which has been submitted to Ofwat.
“We intend to fully cooperate with Ofwat on this matter.”