Fortunately for Van Dieman Brewing, they came prepared.

"We've been going for about 11 years, so 12 months ago we decided to do some scenario work around what would happen if keg supply was pulled, if Bass Strait closed, how would that look for our business?" head brewer Will Tatchell said.

"At the time we were thinking, 'as if this will ever happen'. But then it happened. We pulled up that data and looked through it, and in the end it made it easier for us to work through."

After initial beer panic buying saw their sales soar 50 per cent, demand then plummeted. The closure of pubs and restaurants also hit the Evandale-based brewery hard.

They bought kegs back off venues to keep in cold storage until the economy reopens, and beer in the tank was diverted to their packaged product, rather than kegs.

But declining sales mean the packaged beers are also piling up.

Online accounted for 30 per cent of their sales pre-pandemic, but that figure is now close to 90 per cent.

"That initial panic buying stage looked good to carry us through, but then it slipped back to slower than usual patterns," Mr Tatchell said.

"At the moment we're pretty much just shifting debt sideways. It's just waiting for us on the other side once it all starts off again.

"Buying local will be the key. Whether it's the local brewer, local grocer, the community can create jobs through purchasing at local businesses."

While small-scale brewers have avoided pouring beer down the drain, it was a different story for the bigger players.

James Boag's Brewery also bought excess kegs back from pubs, but had no other option than to pour it down their trade waste systems.

The Launceston operations did not have the same advantage as some of their mainland Lion counterparts, which were able to transfer much of their excess beer into biogas.

Boag's head brewer Nathan Calman said wasting beer was far from ideal.

"That's not something that you like to do, but it was the right thing to do, because when pubs reopen people expect to have fresh beer when they venture back out," he said.

"Some of the keg beer volume we've seen transferred into the small pack products like cans and stubbies.

"We're actually producing our first runs of kegs this week because we're slowly starting to see orders come in for keg products, so that's quite pleasing."

In the meantime, Boag's has been providing 1.25-litre growler bottles to pubs which wanted to provide a tap beer option with takeaway food.

While Boag's could not quantify how many litres of beer had been poured down the drain, Lion has withdrawn more than 200,000 kegs nationwide since the start of the pandemic.

A report from Alcohol Beverages Australia found that April was the worst month on record for the sales of beer, wine and spirits.

Cider suffered the biggest decline at 61 per cent, while beer declined by 44 per cent. Small-to-medium wine businesses reported volume losses of up to 70 per cent due to their reliance on restaurant trade.

Major wine brands reported much smaller losses.

Distillers also suffered heavy losses, with revenue declining more than 80 per cent due to the loss of regional tourism.