Many times, large ice chests are not accommodated with a drain plug. It is a very curious lack of forethought on the part of the manufacturer considering the weight of a large ice chest that has been filled with ice. If you find this inconvenience too much to work with you can always install your own drain plug with just a couple hours time and a few easy to find items.
Step 1 - Setting Up a Location for Drain Plug
Determine where you would like to install the drain plug. Make sure that the plug is in a low location on the ice chest and on a side of the ice chest where it is less likely to be bumped and broken off. Once you have chosen the appropriate location, a good suggestion would be on the same side as a handle, put masking tape inside and outside the chosen location. Measure from the top of the opening of the chest on the inside and outside to get distance. Put enough tape on the inside of the cooler to ensure that you have the proper site for the drill covered. The tape will keep the drill bit from chipping and cracking the plastics of the ice chest.
Step 2 - Drill Hole
From the outside of the ice chest, begin slowly drilling using a hand drill. Avoid using an electric drill because it may cut too quickly and crack the plastic. As you are drilling through keep an eye on the tape to make sure it does not gum up the drill bit. You may have to reverse your drilling on occasion to ensure that the tape does not get caught. Drill completely through to the inside of the ice chest. Extract the drill bit from the hole by reversing the drilling to remove the bit. Don't just pull the bit back through the hole because it can damage the integrity of the hole.
Step 3 - Ready the Drilled Hole for Plug
Once you are completed finished with drilling the hole, use the fine emery paper to smooth the plastic edges. Put silicone around the inside and outside hole and put a rubber grommet on the sides of the plug. Mount the plug into the hole in the ice chest, adhering the rubber grommets to the silicone and affix tightly using the adjustable pliers. Be very careful to not tighten too much and make sure that while installing the plug the drain faucet points down, otherwise it defeats the purpose of the drain.
Step 4 - Test for Leaks
Once you have installed the drain plug tightly with grommets and silicone sealer, wait at least 24 hours. Fill the ice chest with water until it covers the drain hole in the chest. Inspect the area around the drain for water. If you want to be sure, tape a plastic bag around the drain plug and let it sit. After about an hour check the bag. If it does not have water in it, then the drain plug is sound. Push the drain button to make sure that water empties from the ice chest to finalize the test.