Drain Pans help contain and divert the water in the event the hot water tank developes a leak. Believe me, I just experienced this! If my hot water tank would have had a Drain Pan it would have diverted the water when the tank developed a leak at 2:00am causing $2000.00 water damage to our living room. The new Hot Water Tank has a Drain Pan under it. Now if and when it leaks again it will dain into the garage.