A MASSIVE water leak at a North Oxford school was yesterday described as a “timebomb waiting to happen”.

Cutteslowe Primary School is due to reopen on Monday after pupils were sent home on the first day of school on Thursday.

Headteacher Jon Gray said the cause was now believed to be the water supply to an old swimming pool, incorrectly shut off years ago.

And he said the damage – expected to amount to thousands of pounds – could have been “far worse” if pipes had burst during the school holidays, when staff would not have been on hand to spot the problem.

Investigations into the leak were still ongoing yesterday as managers prepared to file for a hefty insurance claim to cover repairs to an astroturf, only installed last year.

Mr Gray said: “We noticed some of our toilets weren’t working so we called in a plumber and when he arrived a leak appeared in the inner courtyard.

“It was very big and was going to cause lots of damage to the building, so we were forced to switch off the water supply.

“We don’t know for certain what caused it at the moment, but it looks like it could be to do with the swimming pool the school had some years ago. When they disconnected it they may not have shut off the water supply properly, so it has then caused the pipes to burst.”

The leak was discovered by a teaching assistant while children were working in their classrooms.

School office manager Kate Murphy said: “We had to act quite quickly and fortunately the kids were still in class. We then put in place an action plan and contacted parents to tell them about the closure.”

Cutteslowe Primary School is run by the Cherwell Academy Trust, which it joined in 2013. Until then it had been run by Oxfordshire County Council, including the period when the swimming pool – believed to have been removed at least 10 years ago – was still in use.

Mr Gray added: “It was lucky we were in school, because this has been like a timebomb waiting to happen.

“The damage that would have been caused could have shut the school for months.”

The county council did not respond to a request for a comment before the Oxford Mail went to press last night.