Workers at the new Perth Children's Hospital are told to drink bottled water, while the hospital's building contractor John Holland investigates the source of lead detected in the water.

The $1.2 billion hospital was due to open later this year.  But the project has run into a series of difficulties, such as the discovery of asbestos in Chinese-supplied roofing panels in July and faulty water piping in March.  But although officials are disappointed, some believe there's still time to correct the problems.

"It should be kept in context," said Health Minister John Day .  "It is a defect.  There's a whole range of issues that need to be addressed before the hospital is opened.  And they've got to do it," he added.

The Western Australian State Government hasn't set a new opening date for the hospital.