Balfour Beatty has informed the school that it is unable to meet the planned completion date that would have allowed pupils to move in to the campus in August 2016. It is now likely to take place in January next year.

In a letter to parents, headteacher Ruth McKay said the delay “is mainly due to an issue with securing a drainage connection with Scottish Water”.

However a Scottish Water spokesman told Scottish Construction Now that the issue will not impact on the school opening programme.

The spokesman said: “Scottish Water can confirm that a sewer connection has always been available. Some network upgrades are required first and the contractor has confirmed that these upgrades will be undertaken.

“As such a sewer connection will be made available in advance. This therefore will in no way impact on the school opening programme.”

Construction of the school, which will replace the ageing 1960s building on Duddingston Road, was delayed for six years because of a long-running row over whether it should be built in Portobello Park.

Construction work finally started in October 2014 after the City of Edinburgh Council successfully took a Private Bill to the Scottish Parliament allowing it to appropriate Portobello Park for educational purposes.

Boasting a swimming pool and two all-weather pitches, the new complex will have space for around 1400 pupils.

The full letter to parents reads said: “I am writing to advise you that unfortunately the opening of our new school will be delayed.

“Our contractors, Balfour Beatty, have informed us that they are unable to meet the planned completion date that would have allowed us to move in to our new school in August 2016.

“This is mainly due to an issue with securing a drainage connection with Scottish Water.

“Work is ongoing to resolve the issue. However, in the meantime we are planning on the basis that we will move into the new school in January 2017.

“There is still a chance that this issue can be resolved more quickly and if that is the case, we would move at the earliest school holiday period which would be the October 2016 break. We are keen to achieve this if at all possible.”