There have been many comparisons written and preferences aired about tap water and bottled water in various publications and forums. Tap water and bottled water are very different in many aspects, but in this article I am concentrating on hygiene issues.
Bottled water is regarded as a food and therefore the hygiene requirements are in line with food production. Certain pathogenic microorganisms are tolerated in tap water, such as Pseudomonas aruginosa, which are not allowed in bottled water. The parasitic cryptosporidium cannot pass through the filters used in bottling water, but sometimes this microorganism finds its way into tap water because it is resistant to chlorination and the filtration process used is not able to remove it. Both these microorganisms can be harmful if ingested by individuals with a low immunity level.
Because cryptosporidium is is a fairly large microorganism, filters prevent access to mains-fed water coolers. However, it is important to have good filtration devices and to have your cooler serviced regularly.
Another issue with mains delivered tap water is the possibility of biofilm build up in the pipe work. If left undisturbed, the biofilm does little harm, but if there is a pressure surge in the water supply the biofilm may rupture and release a large colony of bacteria, often Pseudomonas aeruginosa.
Most contamination of bottled water arises from airborne bacteria or from using older 19 litre bottles which have stress cracking in the form of microcracks. It is difficult to clean and disinfect old and damaged bottles and they should be removed during initial inspection.
Airborne bacteria may enter the water at that critical point during and immediately after filling, before the cap goes on. The time between these operations should be as short as possible and the bottlewasher/filler should be under a positive air pressure, so that airflow is out of the filler rather than into the filler. Remember that a stream of water draws air towards itself by displacement.
Another difference in requirements between bottled water and tap water is that migration of substances from packaging (bottles) follows food regulations, whereas migration from pipe work in municipal supplies follows other, less strict, regulations.
After a long dry spell, the first rains wash all the accumulated bacteria and algae into the rivers and waste water systems, resulting in a huge increase in the bio loading arriving at the water treatment plant. This is detected by the water companies and additional disinfectant measures are taken, but more people seem to get sick about this time.
Although I would prefer to drink bottled water from a hygiene viewpoint, it is extremely important to remain diligent in your bottling plant hygiene operations, particularly if you are in a farming environment, you will be surprised what can float through an open door into your bottling plant.