The Australian Medical Association (AMA) has hit out at efforts to address lead contamination in water at the new Perth Children's Hospital (PCH) with filters, describing it as an inadequate and unsustainable solution.

The State Government said today it would install filters in the hospital's water system in an effort to fix the long-running lead issue, which has contributed to lengthy delays in the $1.2 billion facility's opening.

That follows previous unsuccessful or aborted attempts to address the problem, such as a proposal to flush the system with ice.

Months after the contamination was discovered, the source of the elevated lead levels is still unknown.

But Treasurer Mike Nahan said he was hopeful the issue would soon be resolved, following the installation of filters.

"In recent weeks, a comprehensive flushing program has been and continues to be carried out in conjunction with the installation of filters and continuous testing of the water," he said in a statement.

"The program for addressing the water quality issues has been developed based on the advice of the state's, John Holland's and Water Corporation's expert water quality advisers."

But the prospect of authorities relying on filters to remove any contamination in the water has angered the AMA, which said any solution must involve discovering the source of the problem and replacing all pipes if necessary.

"You cannot build one of the most expensive buildings, one of the most expensive hospitals in the world, spend over a billion dollars, and end up with it full of lead," AMA WA president Andrew Miller said.

"That lead has to come out, filters are not acceptable."

Dr Miller said he was increasingly fearful the Government was attempting to rush to open the hospital before it was safe to do so, urging authorities to ensure there were no safety risks before the facility took in patients.

Health Minister John Day yesterday refused to guarantee the hospital would open in the first half of 2017. PCH is already a year behind schedule after delays which have cost the state tens of millions of dollars.

The Government's mid-year review unveiled last week forecast there would be $77 million in additional costs over four years as a result of the delayed opening.