The five-storey centre had been due for completion in November before the burst pipe in September flooded the building with 40,000 litres of hot water.

ACT Health says it will take significant repairs on levels two, three and four to return the centre to a state where it is ready for patients.

Health Director-General Dr Peggy Brown told a Legislative Assembly hearing on Thursday the work would be expensive and "it probably won't be complete until the middle of next year".

"Unfortunately the delay is going to be much longer than anyone would like."

Dr Brown said most of the costs would be covered by insurance.

The delay is the latest blow for the cancer centre, which will integrate chemotherapy, radiation therapy, haematology, immunology and research and teaching programs.

In June subcontractors claiming they were owed hundreds of thousands of dollars for work on the centre said the project was in chaos.

An ACT Health spokeswoman said there would be no disruption to clinical services because of the flood, and patients would use the existing cancer services at the Canberra Hospital.

The final damage bill would be known once an assessment of the building was complete.

"As soon as more detail about the extent of the rectification works to address damage is known, the project team will work to coordinate the repair work and revise plans for the relocation of services into the new building," the spokeswoman said.

"It will take several months to undertake the extensive repair work once the rectification works have been undertaken, and at this stage it is likely that the move into the new building will be delayed until the second quarter of 2014."