WA's new hospital hit with more woes

Ambulances are set to be diverted from Perth's new Fiona Stanley Hospital for the second time this week, while an engineering problem is assessed.

The first diversion was on Thursday when a water pipe expansion joint burst - the second in less than three months - causing flooding that prompted ambulances to be sent elsewhere and operating theatres to be closed.

The hot water system will now be shut off between 6pm on Saturday and about 11am on Sunday to replace the expansion joint, known as a bellow, meaning patients will not be able to have showers and heating will be turned off.

They will be given extra blankets to stay warm, WA Health acting director general Bryant Stokes told reporters on Friday.

Ambulance and maternity patients will be diverted to other hospitals, but the emergency department will be open for walk-in patients.

"There will be no elective activity going on, no operations and those sorts of things, but patients will be there, they'll be fed and won't be able to have hot showers," Professor Stokes said.

"The rehabilitation centre and the mental health centre unit will remain open and functioning normally."

Prof Stokes said he was very worried about the problem.

"It's terribly, terribly disappointing."

The bellow will be replaced at the weekend and the other 51 bellows at the $2 billion hospital will be examined.

Prof Stokes said the bellow appeared to have had the same problem as the one that ruptured in April, which had been sent back to the manufacturer for examination, with a preliminary report indicating a central component had failed.

"Now what that is due to, we're uncertain, but presumably the manufacturers will tell us something about that," he said.

The bellows are meant to last for up to 100 years.

Prof Stokes said he did not know if all of the hospital's bellows had been made by the same manufacturer, but that would be asked at a meeting with construction managers on Tuesday.

He said Perth's other hospitals would cope at the weekend.

"We haven't had any ambulance ramping for nearly a week now."