I reuse polyethelene 2.5-gallon theatrical fog fluid tanks for water storage. The fog fluid is a glycol, and the tank will smell for a while. I first rinse the tanks to get all the gross product residues out. I then begin a leaching process by filling the tank with very hot water and let it sit until cool. I then repeat the process multiple times until there is no smell. I do two more leachings after that.
Another point that I thought was missed is biofilms. These, like slimes, adhear to the walls and are almost impossible to get rid of. E. coli is one of these film producers. This is why I hate trying to reuse milk jugs. You can never get these biofilms out of them completely. I like peach tea, and within a couple of days, you will notice stains on the walls of the reused milk jug from incomplete removal of the biofilm. Only use jugs that came from the factory with water in them. I can use a water jug for months before any films begin to form. – Capt Nemo