Two brothers are suing the brewer of Budweiser for overstating the alcohol content of the beer.

Two brothers are suing the brewer of Budweiser for overstating the alcohol content of the beer. Photo: Bloomberg

Anheuser-Busch InBev NV, the world's biggest brewer, is being sued sued by two brothers for overstating the alcohol content in its Budweiser beer.

AB InBev routinely adds extra water to its finished products to produce malt beverages with significantly less alcohol than displayed on its labels, Thomas and Gerald Greenberg say in a complaint filed in the US federal court in Philadelphia.

The company's exaggeration of the alcohol content violates Pennsylvania's consumer protection statutes, according to the complaint.

"AB's customers are overcharged for watered-down beer and AB is unjustly enriched by the additional volume it can sell," according to the filing.

The complaint accuses Leuven, Belgian-based AB InBev of also mislabelling the amount of alcohol in Bud Ice, Bud Light Platinum, Michelob, King Cobra, Busch Ice, Black Crown, Bud Light Lime, Hurricane High Gravity Lager, Natural Ice and Michelob Ultra.

The men didn't say in the complaint how they determined the alcohol content of the beer.

The Greenbergs said they routinely bought as many as four cartons of Budweiser a month during the past four years, with the contents labelled as having an alcohol content of 5 per cent.

They claim that AB InBev keeps the alcohol amount for each batch of malt beverage at specifications above the desired final product at least initially, then adds water and carbon dioxide in the final stage of the brewing process.

The company began using in-line alcohol measuring instruments known as Anton Paar meters that can measure the alcohol content of malt beverages to within hundredths of a per cent, according to the complaint.

They say the brewer uses the precision technology to shave the alcohol content instead of providing a product based on the stated label.

"Even though AB knows the true alcohol content of its products, it intentionally and falsely overstates the alcohol content of its malt beverages," the Greenbergs say in their complaint.

They are seeking to represent everyone who bought products in Pennsylvania in their bid for damages exceeding $5 million and a court order requiring the company to alter its advertising.

Bloomberg