Beer lovers across America have accused Anheuser-Busch of watering down Budweiser, Michelob and other brands in class-action court cases seeking millions in damages.
The lawsuits, filed in Pennsylvania, California and other states, claim consumers have been cheated out of the alcohol content stated on labels.
Budweiser and Michelob each boast of being 5% alcohol, while some "light" versions are said to be just over 4%.
The lawsuits are based on information from former employees at the company's 13 US breweries, some in top-level plant positions, according to lead lawyer Josh Boxer of San Rafael, California.
"Our information comes from former employees at Anheuser-Busch who have informed us that as a matter of corporate practice, all of their products mentioned (in the lawsuit) are watered down," Mr Boxer said. "It's a simple cost-saving measure, and it's very significant."
The excess water was added just before bottling and cut the stated alcohol content by 3% to 8%, he said.
Anheuser-Busch InBev called the claims "groundless" and said its beers complied fully with labelling laws.
"Our beers are in full compliance with all alcohol labelling laws. We proudly adhere to the highest standards in brewing our beers, which have made them the best-selling in the US and the world," Peter Kraemer, vice president of brewing and supply, said.
The action involves 10 Anheuser-Busch products: Budweiser; Bud Ice; Bud Light Platinum; Michelob; Michelob Ultra; Hurricane High Gravity Lager; King Cobra; Busch Ice; Natural Ice; and Bud Light Lime.
Anheuser-Busch, based in St Louis, Missouri, merged with InBev in 2008 to form the world's largest alcohol producer, headquartered in Belgium. In 2011, the company produced 10 billion gallons of malt beverages, three billion of them in the US, and reported 22 billion dollars (£14.5bn) in profits from that category, the lawsuit said.