Second hand shipping containers make excellent storage units as they are portable, secure and watertight. If you are planning to get years of use out of a storage container, it is important to check the container is structurally sound with no holes or large areas of rusting. As shipping containers are built to be durable, withstanding numerous journeys across seas, often stacked up to eight high, they have a useful lifespan of around twenty years, so buying second hand is still a worthwhile economic investment.