Argon (Ar) and water

Argon is a naturally occurring noble gas. Small amounts dissolve in water, but argon does not chemically react with water under ordinary environmental conditions. Its presence in water is mainly a question of gas solubility and local geological conditions.

Argon in water

Argon dissolves physically in water rather than forming a stable reaction product. At equilibrium, the dissolved concentration depends on temperature and on the argon pressure above the water; this relationship is described by Henry’s law. Water in contact with air contains a small amount of dissolved argon. The gas can leave the water again when temperature or pressure conditions change.

Argon also occurs naturally in rocks. Most terrestrial argon is argon-40, which is produced by the radioactive decay of potassium-40. Geological sources and gas exchange can therefore influence the argon measured in groundwater.

Environmental and health considerations

Argon is chemically inert and has no known biological role. The main recognized safety hazard is from argon gas accumulating in an enclosed or poorly ventilated space, where it can displace oxygen and create an asphyxiation risk. This inhalation hazard is distinct from the presence of small amounts of dissolved argon in water.

Argon removal from water

Argon is a dissolved gas, so any reduction is generally handled through physical gas-removal methods rather than chemical reaction. Whether degassing is needed depends on the water’s intended use and operating conditions, including pressure and temperature. There is no single argon-removal process that applies to every water system.

Last reviewed: 31 October 2026 by Lenntech.