The water regulator has warned companies it “won’t hesitate” to take action if they fail to show they can protect customers in extreme weather such as the Beast from the East.

Ofwat ordered Thames Water, Severn Trent, Southern Water and South East Water to submit detailed action plans by today setting out how they will avoid future repeats of the failings that left thousands of homes and businesses without running water during the extremely cold weather in February and March.

The regulator’s review of how companies dealt with the Beast from the East, published in June, found that over 200,000 customers in England and Wales were left without water for more than four hours and over 60,000 customers did not have a water supply for more than 12 hours, while some people were without water for a week.

It has said it wants improvements in emergency planning, preparation, response, communication and payment of compensation from the companies whose customers were badly affected.

The Beast from the East brought temperatures which failed to rise above freezing in some regions along with huge dumps of powdery snow, freezing rain and strong winds.

A fast change in temperature led to burst pipes, but Ofwat said the weather was forecast in advance and a number of companies appeared to have “fallen well short on their forward planning and the quality of support and communication they’ve been providing, leaving some customers high and dry”.

Ofwat said it will now carefully scrutinise the companies’ plans and intends to publish a response by mid-November, adding it will “step in” if it believes that any company’s plan does not go far enough.

Ofwat chief executive Rachel Fletcher said: “The harsh weather in the spring left many customers out in the cold with no running water, in some cases for days.

“While a number of water companies and their hard working staff stepped up and did well by customers, others fell well short, particularly when it came to providing bottled water, help for the most vulnerable, or clear, timely communication.

“We expect the companies that let their customers down to have learned the lessons of what went wrong during the freeze and thaw, and to show that they are now prepared to protect their customers, whatever the weather brings.

“This would be a great result for customers. If companies do not convince us of this, we won’t hesitate to step in.”

Consumer Council for Water chief executive Tony Smith said: “Water companies need to prove that they have listened to consumers and really learned lessons from the service failures we witnessed in March.

“Customers will want to know that these plans are tested and ready, and we’ll be expecting a tough response from Ofwat should any of the company plans fail, or further problems occur in future.”