Is it advisable to avoid drinking bottled water obtained commercially whenever this can be avoided?

This is good general advice, one reason being that the lifeforms we point out are important adjuncts for human well-being will decline greatly, in water that is stored for lengthy periods closed off from the atmosphere. And so, water quality simply declines, and has a shelf life with respect to that property. This is in addition to other potential negatives, that the containers are not ideal for disseminating bottled water, as the plastics leach chemical constituents into the water over time, and the source of the water is completely unknown to the consumer. This carries with it the additional risk of adulteration, let alone the fact that a water source containing many undesirable chemicals might be used for convenience in the manufacturing. It is not all a question of palatability, whether there is an unpleasant taste or odor present. Many unseen constituents can have adverse consequences when ingested and absorbed into the body. These grow over time through commercial water supplies because of recycling. So this is one of the major ongoing pollution problems faced by humanity, as fresh water is not only scarce, it is increasingly less healthy due to recycling, using methods that are not effective in reducing many contaminants from returning to the consumer again and again.