How long your tank will last depends upon your application. The chemical being stored, the temperature and what you are using the tank for (mixing, transport, storage, etc.) all affect the lifespan of your tank. Some chemicals will permeate the tank wall and accelerate the aging process by changing the molecular structure of the resin. An example of this is sodium hypochlorite (industrial or swimming pool bleach), which reacts with heat (elevated temperature) or light (UV) and releases free radical ions that attach to the polyethylene (or other) resin. Over a relatively short timeframe, these ions will weaken the tank wall and cause something called “environmental stress cracking” and the tank should be replaced. Periodic flushing of the tank will prolong the life, but it still won’t last as long as a tank holding water, for example.

Source: FAQs - Peabody