Healthy kidneys balance the amount of fluid that enters and leaves the body. If your kidneys can't maintain this fluid balance, you may need to limit your fluid intake. Always talk with your healthcare provider and ask how many ounces of fluid you can have every 24 hours. For accuracy, it's helpful to use a certain glass or mug and measure how much fluid it holds. Some glasses and mugs may look the same size. But they can hold different amounts of fluid. The information below can help.