Oxygenated drinking water is an effective way to separate the gullible from their money. While it is true that levels of dissolved oxygen may be increased in water, the benefits are seen only by water-breathing creatures. Humans do not absorb significant amounts of oxygen through their digestive systems. Several deep breaths will do more to increase blood oxygen levels for a human than will a quart of high-priced oxygenated water.
What is Oxygenated Water?
By increasing the atmospheric pressure around water, or bubbling diffused high-oxygen air through water, the level of dissolved oxygen in water will be increased. This is a measurable fact. When vendors sell oxygenated water, it is possible to sell water with a higher level of dissolved oxygen than will be found in tap or regular bottled water.
Who Benefits from Water with a High Level of Dissolved Oxygen?
Fish and many amphibians will draw more oxygen into their systems if they are in water with a high level of dissolved oxygen. Their gills are designed to draw oxygen from water. If your local area reports a "Fish kill" where a lake or river sees an unusual number of dead fish, the most likely causes are pollution or low levels of dissolved oxygen. Most states make regular checks of the levels of dissolved oxygen in their lakes and rivers as a method of determining the health of the local ecosystem.
Since oxygenated water should end up in a human's stomach, the higher levels of dissolved oxygen would only be able to transfer from the water into the bloodstream through digestion. Humans draw oxygen into the bloodstream through respiration. Our lungs are designed to supply oxygen; our digestive tract supplies the other essential nutrients. The amounts of oxygen added to the the bloodstream through ingestion of a quart of highly oxygenated water will be less than the oxygen added by a few deep breaths.
Benefits of Oxygenated Water
In most cases oxygenated water is made from sources as safe as tap water. It should be as well-filtered and clean as normal bottled water if it is consumed before its expiration date. Like bottled waters, most oxygenated waters have removed the chlorine or chloramines added by the municipal water source to prevent contaminants from forming over time. When the higher levels of oxygen are introduced, they may have an oxidizing effect on residual waterborne organics. While drinking oxygenated water won't hurt a human, pouring that water into the human's aquarium will show an improvement in the health of the human's fish. As with other "enhanced" waters, the main benefits to humans fall into the range of the placebo effect. No consumer wants to believe they spent 500 times as much as the cost of a pint of tap water to only drink tap water. They may feel extra energy for a while as the alternative to feeling foolish.
Risks of Oxygenated Water
Beyond spending even more money for tap water than the buyer would spend buying bottled water, the extra filtration seen in most oxygenated waters means the expiration date is important. A bottle of oxygenated water will most often have less disinfectants and a more hospitable environment for waterborne pathogens than tap water. Unlike other "enhanced water" scams like hexagonal water, oxygenated water may provide a positive environment for pathogens. Do not drink a bottle of oxygenated water after its expiration date.