If labeled as a "Hamburger," it can contain all beef or beef and beef fat. Other permitted ingredients include dry seasonings like spices and flavorings. Water (and other liquids) and fillers (like breadcrumbs and flours) are not permitted. Products including these ingredients may be called "Beef Patties" and the added ingredients must be listed on the label. https://ask.usda.gov/s/article/Can-hamburger-meat-contain-ot...
For the US, obviously. You sound like you may be in another country.
If labeled as a "Hamburger," it can contain all beef or beef and beef fat. Other permitted ingredients include dry seasonings like spices and flavorings. Water (and other liquids) and fillers (like breadcrumbs and flours) are not permitted. Products including these ingredients may be called "Beef Patties" and the added ingredients must be listed on the label. https://ask.usda.gov/s/article/Can-hamburger-meat-contain-ot...
For the US, obviously. You sound like you may be in another country.
I'll add that LFTB (https://en.wikipedia.org/wiki/Pink_slime), which is meat, can be up to 15% of the content of ground beef.