Metropolitan Perth, the Peel region and South West have finished their five-day lockdown after WA posted a fifth consecutive day of no new community cases.

Almost 50,000 tests were conducted during the lockdown as West Australians heeded calls to get checked.

"Like many Western Australians, I'm so relieved we have got to this point and we can get businesses and our economy back open with full confidence," the premier said on Friday.

"We got through this and it's a credit to each and every one of you."

A range of restrictions remain in place for Perth and Peel until 12.01am on Sunday, February 14.

All residents, including teachers and high school students, must continue to wear masks while outside of their homes except for during vigorous outdoor exercise.

A 20-person limit will be imposed on all private indoor gatherings, while a four square metre rule and a cap of 150 attendees will apply to hospitality and retail venues and weddings.

Restaurants, pubs and bars can only have seated service and only essential travel is permitted in and out of the combined restricted zone.

Individuals will also face penalties for not using the SafeWA QR code system or written contact registers.

"It is absolutely vital this becomes a habit," Health Minister Roger Cook said.

"It must be part of your routine. The more you do it, the more you help all of us."

The premier has announced a $500 offset on electricity bills for small businesses and charities affected by the lockdown.

It is expected to be taken up by about 85,000 customers at a cost of about $43 million and to provide, on average, up to two months of bill relief.

"I know this won't cover the cost of a lockdown, I understand, but I hope it does provide some form of help," Mr McGowan said.

The government has defended forcing more than two million people into lockdown over what has proved to be just be one case - that of a security guard at the Sheraton Four Points hotel who unwittingly roamed the streets of Perth while infectious.

Mr Cook is confident any isolated cases that may emerge in coming days won't result in the lockdown being reinstated.

"Particularly if it's among one of the close contacts, we know that person would have been isolated, we know that person would have been tested extensively so we have great insights," he told Perth radio 6PR.

"So in that instance, we certainly wouldn't back down on our transition out of this."

Prime Minister Scott Morrison has granted the premier's request for WA's cap on overseas arrivals to remain at 512 per week until the end of February.

Officials are continuing to investigate how the guard contracted the highly contagious UK strain of the virus from a sick guest.

The guard had been stationed on a chair about three metres from the guest's room but they are not believed to have had any face-to-face contact.

Authorities believe the virus was transmitted either by airborne transmission or surface contamination.

Anyone working in a "high-risk situation" in quarantine hotels is now required to wear a face mask and protective eyewear at all times.

The government will also introduce saliva tests between shifts for hotel quarantine workers.

Australian Associated Press