Contractors have had to stump up hundreds of thousands of pounds to resolve problems caused by a frozen-pipes blunder at four Bradford schools which are under construction.

Integrated Bradford, the consortium of contractors working in partnership with Bradford Council on its multi-million-pound Building Schools for the Future programme (BSF), has so far spent about £600,000 repairing the damage which occurred when water was left in under-floor heating pipes over the winter.

Grange Technology College and Hanson School in Bradford, Beckfoot School in Bingley and Greenhead High School in Keighley were all affected.

They are being rebuilt in the second phase of the BSF scheme and are due to be completed by spring next year.

As exclusively reported in the Telegraph & Argus in March, water inside heating pipes at each of the construction sites froze, cracking the pipes and concrete floor slabs laid over them as temperatures repeatedly plunged below zero.

The Council confirmed the situation occurred after contractors had filled the heating systems with water to test for leaks and failed to drain them before they were covered in the concrete. The resulting problems left senior Council officers seething and councillors questioning how such a basic mistake could have occurred.

Since then, on-site working hours have been extended at each school. Revised conditions mean work is carrying on at the three schools in Bradford and Keighley until 11pm and at Beckfoot until 7pm on weekdays.

Integrated Bradford insists the schools will still open as scheduled for the start of the summer term after Easter next year.

Its general manager, Tony Smith, said: “We are pleased to report that all the schools affected by frozen pipes during the winter are now back on track for completion by the original contract dates.”

But the Council has stressed that it will not pay a penny of the extra costs which will have to be borne by Educo, a consortium of construction giants Costain and Ferrovial Agroman, which is responsible for the design and building work for the BSF programme.

Speculation is also mounting over the security of BSF funding for schemes across the country after the new coalition Government announced a huge spending review for autumn.

But Councillor Ralph Berry, the Council’s executive member for children and young people, said the local authority had gained approval for £337m in funding for the third phase of its programme “just in time” and he was confident that it would be protected from any cuts.

He said: “We have done all we can to ensure the schemes are fit to implement.”

Elsewhere the situation is less sure. Kirklees Council leader Councillor Mehboob Khan has written to the Government asking for clarification on his authority’s £280m BSF programme.