The Emergency Services Agency said about 80 people were evacuated from the complex on Daley Road on Monday morning.

All four floors of the building were damaged by the water leak.

ACT Fire & Rescue attended the incident, and at 12.30pm, crews were attempting to isolate power in the building.

Salvage operations were still ongoing at Building 40 at 1pm.

Building 40 is listed by the ANU as Bruce Hall, the university's oldest undergraduate residence.

A Bruce Hall spokesman confirmed the evacuation but said students and staff had since re-entered the building.

An ACT Emergency Services Agency spokeswoman said the ANU would handle all maintenance work related to the water damage.

An ANU spokesman said the flooding was caused by an accidental activation of the sprinkler system in the Packard Wing of Bruce Hall.

“No one was hurt in the incident but students were evacuated as a precaution,” he said.

The spokesman said one room has been extensively damaged by the flooding while another three rooms sustained minor damage.

The affected students will be allowed to return to their rooms once cleaning and checks of the electrical systems have been carried out.

“Alternative accommodation is being arranged for the residents whose rooms were damaged,” said the spokesman.