A burst water main flooded parts of the school, fortunately before any students had arrived.

The water main on an adjacent property, near the Flagstaff Road entrance burst sometime Friday morning and inundated parts of the school.

A Sydney Water spokeswoman said the leak was reported at 6am and crews were on site by 7.20 am.

There is understood to be substantial damage.

A Department of Education spokesman said while no classrooms were damaged by the significant volume of water that flowed over school grounds, the school was unable to accommodate its 620 students.

The school used social media to ask parents to keep their children home on Friday if possible.

‘’If this was not possible, staff would supervise students arriving at school, and less than six students attended the school in this capacity,’’ the spokesman said.

A Sydney Water spokesman added that crews had isolated the main to stop water flowing onto the road and into the grounds of the school.

The crew then worked to repair the pipe and restore the area to its previous condition.

‘’Warrawong High School is closed today – we encourage the community to follow the school’s instructions and the instructions on emergency services who are on site,’’ the spokeswoman said.

‘’We have a customer liaison officer on site to help impacted customers, including the school, in the short term.

‘’Sydney Water will also assist customers who need to lodge a claim for any damage or loss incurred as a result of this main break. We apologise for the inconvenience.’’

Warrawong High School is expected to operate normally on Monday, November 27.

The Department of Education spokesman said the school will again use social media to confirm this with parents.