The British Beer & Pub Association says the amount has fallen by over 8% to 3.81 litres per head in the first half of 2009 compared with 4.15 litres in the same period of 2008.
The last time the nation's alcohol consumption fell by more than this was during 1948 when it dropped 11% in a year. The numbers are from official HM Revenue & Customs data and have been compiled by the BBPA.
The amount consumers drink has been declining for four and a half years, since a peak in 2004. On current trends, by the end of this year, the it will be down to the same levels recorded in 1999.
The numbers call into serious question alcohol policies designed to reduce drinking in the whole population, says the BBPA.
It added that claims by some academics and medical lobby groups that a fall in total consumption would lead to significant social benefits, such as a decline in alcohol related hospital admissions, are not being borne out by the facts.
It said: "With over four years of falling consumption, the academic theories in the governments much quoted Sheffield Study can now be tested against experience in the real world. According to the Sheffield calculations, the fall in consumption of over 6% between 2004 and 2008 should have resulted in around 20,000 fewer alcohol-related hospital admissions in 2008 and on current trends, around 50,000 fewer admissions this year. However, the medical profession regularly reports rising hospital admissions.
"The consumption data shows that the theory of reducing everyone's drinking to tackle alcohol harm does not work in practice and that targeted policies would be more effective. Despite this clear trend, the government continues to press ahead with a wide range of measures designed to control alcohol consumption at national level."