**There is no universal minimum liquid level for slow cookers.** Use the amount specified by the recipe and check your cooker’s manual for any model-specific requirements. USDA guidance says to add the amount of liquid suggested in the recipe. [USDA slow-cooker guidance](https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/slow-cookers-and-food-safety)

The recommendation to keep a cooker half to three-quarters full refers to **the total contents—food plus liquid**, not the water level. It helps the cooker perform predictably within the recommended cooking time. [Crock-Pot cooking tips](https://www.crock-pot.com/on/demandware.store/Sites-crockpot-Site/default/Support-Show?cfid=help-and-how-to-use-cooking-tips-faq)

For your turkey, use the **½ cup of water specified on the package**, provided your cooker matches the size described and its manual permits that method. The turkey releases juices as it cooks, and a covered slow cooker loses very little moisture through evaporation. The roast does not need to be submerged.

Start with the roast fully thawed, keep the lid on except for the instructed temperature checks, and follow the package’s four-hour checkpoint and final temperature. If your cooker is substantially larger than the specified 8-inch model, use a suitably sized cooker or the package’s oven method; adding water to reach three-quarters full would substantially change the recipe.