Paraquack raises a valid concern. If this is an Intermediate Bulk Container (IBC) these are typically used to transport bulk chemicals, and these chemicals can penetrate the semipermeable plastics in some cases.Are you sure they are ok to store water in with no bad chemicals used in them previously?
These should be triple rinsed before use but without knowing what it contained previously you cannot be sure what to use for rinseate.
I would check with the reseller to see if he/she knows what the IBC first contained.
I know you are a smart cookie, Ripon, but buyer beware....