Coopers Brewery director Tim Cooper said the company's overall sales were severely affected, with April's figures down by 50 per cent.

"We saw a bit of buying up in March in terms of packaged beer but April was a low month," he said.

"May is starting to look a bit more promising."

Mr Cooper said with pubs reopening on Monday, keg production was ramped up this week.

Keg sales make up about 20 per cent of the group's total revenue.

"Originally the prime minister said it could be six months before businesses get back to normal so we were expecting that," he said.

"It's great news that pubs in SA can start operating again and get people back in the doors and keeping people employed."

Coopers Alehouse publican Nick Sando said he was looking forward to opening the doors again, even though the limits on numbers would not be viable over the long term.

Under the new arrangements, pubs can serve up to 80 people, provided they are seated and provided they are in separate areas catering for 20 people each.

"The hotel is licensed for 500 normally so 80 is still a long way off," Mr Sando said.

"It's going to be challenging at first, but hopefully, as restriction ease, we'll get back to normal as soon as possible."

Premier Steven Marshall said he was convinced local businesses understood the importance of complying with restrictions, to help keep COVID-19 under control.

"We are opening up South Australia as fast as we possibly can whilst protecting South Australians from the possibility of a second wave of infections," he said.

"A quick drink in the pub after work is a great part of our social life and it will be fantastic to welcome that back from Monday."

Australian Associated Press