We have a number of 21 gallon poly fuel tanks that can be plumbed and used for other liquids such as potable water.
These would make a great DIY project for campers, gardeners, or farmers who are in need of a lightweight auxillary tank. Would probably mount just fine onto a four wheeler rack.
No limit as to how many you can purchase, and priced at $3 each.
Located in Hays.