HDPE is ideal for containing highly concentrated chemicals, and protecting against exterior damage. It is also BPA free, meaning that humans and animals alike are safe to consume or come into contact with the contents inside.
You'll often find HDPE used within landfills, or for chemical containment. This is due to its high ability to withstand corrosion. HDPE is also fish safe, making it a good choice for ponds who want to harbour aquatic life.