It's a 2 gallon water jug. Up to now I've used empty gallon containers (cider, milk, etc.) to store and carry water, but I find that they're definitely not made for multiple uses. They're so thin that they'll eventually develop leaks and wrap and crack over time.
These water jugs are made of plastic, but they're extremely sturdy and thick. The size is actually perfect—2 gallons is about the limit of what I can carry around comfortably, so I can hit all the plants, humidifiers, and whatever else around my house needs water. It's also good to have as an emergency water supply.
