They are called Rubbermaid stock tanks and I just bought a 300-gallon one from a local nursery to use as an outdoor pond for plants. They had to order it for me because the largest ones they carried were 150 gallons. What is nice is that they have a drain plug. Rubbermaid is not the only manufacturer of stock tanks. Rubbermaids seem to be the only ones available in this area. Mine is 25 inches deep with a diameter of about 63 inches. One company makes a plastic one like Rubbermaid, but it is 8 feet long, about 25 inches deep and about 40 inches wide. I couldn't get it locally and the shipping charges would be very expensive. Google stock tanks and they will give a lot of information on what's available.