More than a year since Perth's $1.2 billion children's hospital was supposed to open, that date is now unknown partly because builder John Holland hasn't found the source of lead that has contaminated the facility's water supply.

The WA government on Tuesday defended awarding the contract to John Holland despite the new hospital being beset by a litany of problems. Labor has accused the government of lying about the progress of the project, after obtaining internal state government reports through a freedom of information request that reveal…