All the water we use, to drink, to shower, to wash dishes, all of it is full of life. What varies from one water source to another is not that there is life, but its composition, which species we will find and which ones we will not.
This composition depends, above all, on the first origin of the water. For this reason, bottled water also contains bacteria. Because the word "clean", in the context of water, will never mean "sterile" .
No to sterile water
As Rob Dunn explains in his book Home Alone? Even when we take a hot shower at home, there are predatory bacteria that:
Right now, in every home’s shower head, these tiny "pikes" are clinging to other bacteria, piercing their sides and releasing chemicals to digest them. The biofilms also support protisas that eat the "pikes", and even nematodes that feed on the protisas, as well as fungi that carry out their own fungal work. This is the food chain that falls on us every time we shower.
Some studies have even found that bottled water contains a much higher density of bacteria than tap water. In this study , for example, 57 samples of 5 categories of bottled water were purchased from local stores .
We need not worry. These bacteria are good for our health . Some of these beings are even good indicators of the good health of the water. Water can be safely consumed if it does not carry pathogens (or it contains them in very low concentrations) and if it has concentrations of toxins low enough not to cause disease (in this case the degree of concentration will depend on the toxin in question).
For example, this other study found that environmental bacteria did not produce significant virulence-associated enzymes, were not acid resistant, were susceptible to semisynthetic antibiotics, and did not produce appreciable cytotoxicity. These naturally occurring aqueous bacteria were adopted from an aquatic environment, did not grow well under conditions analogous to the human host, and did not have the characteristics associated with virulence .