Hydromassage consists of the projection of underwater jets of water and air for therapeutic or relaxation purposes. Usually it uses hot water, which can be mineral-medicinal or not. Therefore, ideally it combines the mechanical or pressure, thermal and chemical effects and those of the minerals in the thermal water. When using drinking water, salts and aromatherapy essential oils are normally added. The mechanism for projecting the high pressure water can be installed in a bath for one person. In this case it is called a hydromassage bath. If the water container can hold more than one person, it is usually called a jacuzzi, after the inventor of this system, the Italian-born American Candido Jacuzzi, who was searching for a cure for his son, who was suffering from rheumatoid arthritis.
It is also known as a spa, although this name is also used to refer to hydrotherapy centres that use fresh water.
Hydromassage pools can be found either indoors or in the open air. They may also have an area with underwater jets of water.
If they have external jets, areas with water currents, wave machines or other mechanisms that produce movement in the water, they are called active pools.
Hydromassage stimulates blood circulation and relaxes muscles, which aids improvement in the condition of people suffering from a large number of illnesses, mainly rheumatic. It also relieves joint pains and produces a general sedative effect.
The water is usually purified with ozone. Chlorine is not recommended as it harmful to the skin and respiratory tracts.