According to the trade body, the waste is equivalent to £331m in sales.
BBPA chief executive Emma McClarkin has described the situation as 'heart breaking'.
Barrelled beer not sold by its best-before date has to be returned to breweries and disposed of.
For pasteurised beers - including most lagers - this is usually about three to four months after delivery to pubs.
For real ales and other unpasteurised beer, the timescale is normally around six to nine weeks.
From industry feedback, the BBPA says that around 70 million pints were thrown away during the first lockdown, with a further seven million wasted in November and an expected 10 million still to go.
In response to the findings, McClarkin has called on the Chancellor once again to extend the VAT cut and business rates holiday to support businesses as they look to reopen.
“Pubs and breweries are effectively having to pour their businesses down the drain” with “no idea or clarity from government on when we can reopen again,” she told the BBC.