Defective construction works at the Austin Hospital have caused extensive plumbing problems, a Supreme Court writ alleges, leading the Andrews government to sue builder Lend Lease for costs "in excess of $20 million".

The legal action cites repeated water leaks following the completion of the hospital's nine-level tower in 2005.

Ambulances outside the Emergency entrance at the Austin Hospital. Credit:Mal Fairclough

And it comes as a section of the hospital's 30-bed intensive care unit has been closed since February because of leaks, which are believed to be affecting other parts of the facility.

The legal action, taken by the Department of Economic Development, Jobs, Transport and Resources, claims hot and cold water piping in part of the hospital is defective and that materials used for plumbing were not "fit for their intended purpose".