Premier Daniel Andrews on Thursday announced a "hard border" will be in place from 11:59pm tonight for 48 hours before a permit system comes into effect from Sunday.

Under the hard border, only freight drivers and those with medical or emergency reasons, urgent animal welfare or as authorised by law will be able to cross the border.

"This was an appropriate thing for us to do and it'll be difficult in those next couple of days," Mr Andrews said.

"Once the permit system is up and running, it'll be a little easier and it will be in place no longer than it needs to be."

IN OTHER NEWS

It comes after fragments of the virus was detected in untreated wastewater taken from Benalla and Portland treatment plants on Tuesday.

The preliminary positive test results, which were received on Thursday, were "unexpected and concerning", as there are no residents of either area known to have had a recent coronavirus illness or diagnosis.

Mr Andrews urged residents of Benalla and Portland, as well as anyone who visited between November 15 and 17 with "any symptoms at all" to get tested and to isolate until they get their result.

Victoria recorded its 20th consecutive day with no coronavirus cases or deaths.

There are three active cases in the state, with 17,161 people tested in the previous 24 hours.

The state's virus death toll stands at 819, with the national figure 907.