To prepare the lettuce for storing, remove the core and run cold tap water into the open cavity until it is full. Turn core side down to drain excess water for at least 15 minutes. Place a Cambro drain shelf in food storage box and place all heads of lettuce on the drain shelf in the box. Place in your cooler. Be sure to use a drain shelf to keep the heads out of the water. Lettuce will absorb water through its porous leaves. It is important to keep the lid snapped on at all times.