The number, severity and frequency of water mains bursts in Swindon has been increasing and it is ‘not normal or expected’.

Bosses at Thames Water, who had been invited to speak to Swindon Borough Council’s Scrutiny Committee, said they could not find a single underlying cause for the problems however.

The frequency of the mains leaks had led to the water company being invited to address the b committee and ask questions, and the session started with public questions.

 Charles Drew, the headteacher of Commonweal School in Old Town said the school had suffered a total disruption to its water supply twice in the last 12 months, one in September and one in May and had to scramble to tell families to keep their children home and to provide improvised online learning.

The regional head of the clean water network Dave Haydon apologised for the disruption.

Former councillor Bob Wright asked about discharges of sewage into the River Ray and said: “It’s counted by length of time and the number of discharges, but do you monitor it by volume of the discharge? If it’s an hour, is it a trickle, or a major gush?

“It makes a difference, and the public would be more able to judge the seriousness of it.”

He was told that the volume of sewage discharges was not recorded.

The water company’s directors gave a presentation on all aspects of the company’s work in Swindon, its assets dealing with sewage and wastewater, groundwater and how it provides fresh water to homes.

Speaking about the breaches of water pipes since the one which shut County Road in May 2023, Mr Haydon said of seven main incidents that different types of pipe were involved; four were UPC plastic pipes, two were cast iron mains and one a glass reinforced plastic main.

Chairman of the committee, Councillor Dale Heenan said: “It’s a concern that it’s not normal, and you don’t know why it’s happening.

“What are you doing to get to the bottom of the matter?”

Mr Haydon said: “We know why each bust happened – what we can’t find is any commonality and a single underlying cause, but it isn’t normal or expected and  we are continuing to look into it.”

There was a discussion of whether the heavy clay soil in some parts of Swindon gets waterlogged in winter and dries out quickly in warm weather and whether this caused movement in the spoil, stressing the water pipes.

As 9pm approached, three hours after the start of the meeting, the subject of the company’s work on the Fleming Way Bus Boulevard development still hadn’t been reached, and Cllr Heenan asked the committee whether it wanted to continue or invite the water company’s staff back again at a later date.

The cabinet member for highways and the environment Councillor Chris Watts said: “I’ve got quite a lot to say about this.”

His suggestion that the committee ask Thames Water back to discuss Fleming Way in detail was accepted.

Thames Water, which is among the worst performing firms on sewage spills, is also in £15 billion of debt.

The business has said it only has enough cash to continue trading until the end of May next year.

The chief executive Chris Weston, this month defended his bonus of £195,000 for his first three months in charge.

Water regulator Ofwat wants to limit the rise in water bills to £19 per year until 2030. But firms such as Thames Water claim this is not enough of a hike if they are to fix leaks in towns like Swindon.

The amount is a third less than what water companies requested, and they believe the regulator had "got this wrong". Thames Water had originally proposed an increase of £191 by 2030.

With the proposed limit, customers will be facing an increase of £99 by 2030.