Artesian bottled water is a naturally pure form of water extracted from an Artesian well. Many consumers favorably compare it to natural spring water in terms of flavor and clarity. The main difference between the two types of water is that spring water is often mechanically pumped from an unconfined aquifer while Artesian water is naturally pumped from a pressurized and confined Artesian well.
An aquifer is a natural collection point for ground water, often more like a sponge than a flowing underground river. Some types of ground water are contained between layers of soft rock, which means a bottler would need to pump the water out mechanically in order to overcome the natural pull of gravity. The underground water table is not under pressure, since the material around the water does not keep it confined.
An Artesian aquifer, on the other hand, is usually surrounded by harder layers of rock. When a drill breaks into the confined aquifer, the water is naturally forced upwards by the pressure. When additional ground water works its way into the confined aquifer through gravity, the pressure is maintained and the Artesian well continues to flow upwards to the surface.
Artesian bottled water is not much different chemically than other forms of bottled water, but the bottler did not have to install expensive mechanical pumps to extract it for bottling. This savings is not generally passed along to the consumer, however, because Artesian water is often marketed as a premium form of naturally pure water. There are only a limited number of Artesian water aquifers which have been drilled for commercial bottled water purposes, and most of them are well-regulated by their countries of origin.
There have been cases of an unacceptably high coliform bacteria count in some Artesian bottled water supplies, but it is still generally considered safe for human consumption. The fact that Artesian wells derive their water from a confined aquifer deep in the water table suggests that it has been naturally protected from agricultural run-off and other contaminants commonly found in unconfined aquifers closer to the surface.
Artesian bottled water is not necessarily protected from harmful bacteria formation, however, and many bottled waters are only tested on a weekly basis, not on a daily basis like municipal tap water sources.