But South Australia's Police Commissioner Grant Stevens conceded that authorities were limited in their ability to enforce the isolation orders.
He said authorities were "relying on people's community and sense of goodwill to do the right thing", and that overwhelmingly people had been complying with orders.
Later on Sunday, Premier Mark McGowan announced entry into Western Australia would be restricted via road, rail, air and sea from 1.30pm on Tuesday, with exemptions for essential services and trucking.
Rottnest Island, a popular tourist location, may be turned into a COVID-19 quarantine zone, Mr McGowan said.
"These are extreme steps but these are extreme days," he told reporters, as 30 new cases were confirmed overnight, bringing the state's total to 120.
The border announcements follow similar moves already made by the Northern Territory and Tasmania.
Cases keep rising
As of 1pm AEDT on Sunday, there were 1,286 confirmed COVID-19 cases across Australia.
NSW Health on Sunday confirmed 97 new COVID-19 cases, bringing the state's tally to 533.
Of those 533 cases, 46 have been contracted locally without an identified source of infection.
The number of negative tests conducted, as of 8pm on Saturday, was 52,130.
In Victoria, food packages will be distributed from tomorrow to people who don't have friends and family who can readily help them get supplies.
State authorities confirmed on Sunday morning the number of the people infected rose overnight by 49 to 278.
Queenslanders have also been urged to stay in their own neighbourhoods to limit the spread of coronavirus across the state.
Premier Annastacia Palaszczuk made the request on Sunday morning, as it was announced the number of cases had jumped by 38 overnight, to 259.
At midday on Sunday, the ACT reported 10 new cases, bringing its total to 19.
Chief Minister Andrew Barr has urged all Canberrans to avoid non-essential travel outside the Canberra region.
Seven people have so far died in Australia after contracting the virus; six in NSW and one in Western Australia.
Coronavirus symptoms can range from mild illness to pneumonia, according to the Federal Government's website, and can include a fever, coughing, sore throat, fatigue and shortness of breath.
As of Saturday morning, only people who have recently travelled from overseas or have been in contact with a confirmed COVID-19 case and experienced symptoms within 14 days are advised to be tested.
If you believe you may have contracted the virus, call your doctor, don’t visit, or contact the national Coronavirus Health Information Hotline on 1800 020 080.
If you are struggling to breathe or experiencing a medical emergency, call 000.