Bread and water
"Bread and water" refers to the most basic of meals. It is a common policy to give prisoners only what is necessary to survive and nothing more.

In 2375, while imprisoned in 's brig for thirty days, Tom Paris referred to Captain Kathryn Janeway's orders that he be given "basic nutrition only" (in this case, leola root stew) as "bread and water". ()  

In 2376, Janeway ordered bread and water only for the prisoner Dala, but Neelix brought her some extra things anyway. This included some tea. Unfortunately for the Talaxian, she threw the drink at him and stole his weapon so that she could escape. ()

de:Brot und Wasser
Foods and beverages