First of all bottled water does not have an expiration date. Like all food products controlled by the FDA they are required to have a best used by date. Still water spring. purified distilled actually has a shelf life of about two years if the seal is intact.
As long as the water is stored properly as you would any other food item you don’t have to worry about plastic leaching into the water. PET is very stable in spite of what the anti bottled water crowd says on here.
Single serve water bottles do not contain any BPA and never have. Even most of the 5 Gallon bottles no longer contain BPA. Plastic contamination from PET bottles is negligible and won’t harm you. BPA is used in the lining of most canned goods. That white coating you see on the inside of a can is BPA.