Those 2.5 gallon containers from the supermarket leak pretty easily especially in hot weather. I've had better luck with the 1 gallon clear bottles. For larger volumes (30 gallons isn't that much) you might look at Aquaflex tanks: www.aquaflex.net . I'm thinking of getting one of the 60 gallon ones and putting it under my bed. Finally, people here seem to like the Reliance 7-gallon Aqua-tainers which are rugged and stackable. At about $10 each the investment for 3 of them is not that large. I don't have any myself but may pick up a couple next time I'm at REI.