Ozone was first used in water treatment in the late 1800s. Ozone is an unstable gas comprising of three oxygen atoms, the gas will readily degrade back to oxygen, and during this transition a free oxygen atom, or free radical is form. The free oxygen radical is highly reactive and short lived, under normal conditions it will only survive for milliseconds. Ozone is a colorless gas that has an odor similar to smell of the air after a major thunderstorm.

Ozone has a greater disinfection effectiveness against bacteria and viruses compared to chlorination.

In addition, the oxidizing properties can also reduce the concentration of iron, manganese, sulfur and reduce or eliminate taste and odor problems. Ozone oxides the iron, manganese, and sulfur in the water to form insoluble metal oxides or elemental sulfur. These insoluble particles are then removed by a separate post-filtration. Organic particles and chemicals will be eliminated through either coagulation or chemical oxidation.

Ozone is unstable, and it will degrade over a time frame ranging from a few seconds to 30 minutes. The rate of degradation is a function of water chemistry, pH and water temperature.

Ozone can eliminate a wide variety of inorganic, organic and microbiological problems and taste and odor problems. The microbiological agents include bacteria, viruses, and protozons (such as: Giardia and Cryptosporidium).