Please understand that the plastic bottles provided in commercial drinking water are very safe when used as intended, that is to say, as a single use for dispensing their product. It is safe to say that bottlers like Dasani, Nestle, and Aquafina use the absolutely safest, FDA products available to man. Their bottling processes are likewise impeccable.
We must understand, however, that depending on the sensitivity of a particular lab analyzer, it can be orchestrated and shown that in some experiment that a minute trace of chemical or substance may come out of the plastic and enter into the bottled water. To be clear, science can be used to make any point to suit any agenda. In my professional opinion, when it comes to the intended, single-use of a commercially prepared bottle of water, the bottles on your store’s shelves are safe.
Remember, when someone claims they have uncovered scientific danger that a plastic bottle may be dangerous, their research also must be applied to things like medical syringes, medicine bottles and other common drinking vessels we all enjoy. Remember also that water is the universal solvent and given surface exposure over enough time, it will eventually dissolve most materials.
Also be in tune to the fact that exposure to extreme temperatures, gases, radiation, and chemicals could cause any bottle to become unstable, but that isn’t what we are talking about here.
The best reason for not reusing the bottled water bottle has to do with water and not the bottle.
Bottled water seldom contains chlorine. As a result, such water is subject to bacterial contamination as it sits in the bottle after it has been opened. Subsequent reuse increases the risk that the bottle will become contaminated. Unlike wide-mouth bottles, glasses, cups, and jugs which are designed to be washed and sanitized, a commercially prepared drinking water bottle is not easily cleaned in between uses. For this reason, reusing bottled water bottles exposes the consumer to contamination of bacteria, viruses and other organic organisms. Be clear, these risks are self-induced and not a fault of the beverages provider. As a side note, if the bottler does not provide a label warning about reusing their bottles, they should.
As a rule of thumb, discard bottles of commercial drinking water 24 hours after opening. Also, wash your reusable bottle after 24 hours of use.