All about Spa Water

All about Spa Water

Water is the source of life.
But why is water so important? What are the different varieties of water? And what are their qualifications?

The different kinds of water

There are three types of water: natural mineral water, spring water and tap water.

Distribution Water is commonly called ‘tap water’. It comes from underground and surface catchments (including rivers). To become clean, it undergoes multiple chemical and microbiological transformations. Before transport, tap water is chlorinated to prevent the growth of bacteria and pathogens.

Source water is a groundwater that is drinkable at the source without any treatment. It meets the same requirements as tap water. Mineral composition may vary, as it comes from various sources, sometimes very different from one another.
However, the composition of a natural mineral water, like the Spa water is always the same.

It’s an underground water with a pristine purity. It must be free of any risk and therefore strictly protected. It must have a stable mineral composition over time. Finally, it can not undergo any chemical or microbiological treatment and finally it must be bottled at the source.

The 3 mineral waters of the Thermes of Spa

The Clementine spring

Rich in bicarbonate and calcium, the water from this spring, heated to 33ºC, supplies the central areas before spreading to the periphery to feed Jacuzzis, bubble seats, massage mushrooms or jets, promising relaxation, invigoration, suppleness…


Natural mineral water located on the northern flank of the Spa massif in a fairly complex geological feature, called the « Fenêtre de Theux ».
The feature contains rocks from the Carboniferous and Devonian eras (350 to 400 million years ago) composed of limestones, dolomites, sandstones and schists.

Its uses
  • Digestion
  • Liver detoxification
  • Balneothérapy
Its characteristics

It contains calcium Bicarbonate.


Ca 70 mg/l SiO2 9 mg/l
Mg 12 mg/l Fe
Na 13 mg/l Mn 9 mg/l
K 10 mg/l Dry residue
275 mg/l
Ci 10 mg/l CO2 g/l
C04 10 mg/l
NO3 5 mg/l pH 7,1-
HCO3 275 mg/l rH 25
The Reine (Queen) spring

Very low in mineral salts, it is used as a drink to eliminate toxins.


Natural mineral water located within the fissures in the demineralised, quartz phyllite Cambrian bedrock, (500 million years).
This type of natural mineral water originates from a deposit located between the 575 m depth marker of the post primary peneplain and the base of the strongly demineralised zone at a depth of 400 / 440 m

Its uses
  • Diuretic therapy
  • Rehydration
  • Low sodium dietary regime
Its characteristics

Very low mineral content


4,5 mg/l SiO2 7 mg/l
Mg 1 mg/l Fe
Na 3 mg/l Mn 0,025 mg/l
K 0,5 mg/l Dry residue
33 mg/l
Ci 5 mg/l CO2 g/l
S04 4 mg/l
NO3 1,9 mg/l pH 6
HCO3 15 mg/l rH 20
The Marie-Henriette spring
This is the oldest of Spa’s waters (400 years). It is the one that supplies the water for the thermal spa treatment.
It is a naturally iron bearing and carbonated water.
Its properties mean it is used for carbonated baths, peat baths (pains and rheumatic ailments), inhalations, (in this case the active agent is the sulphur contained in the water).
The Marie-Henriette spring comes from 3 catchments sharing the same attributes and originating from the same aquifer. Marie-Henriette, Wellington and Tonnelet. It arrives at Les Thermes through the same pipe.
In the entrance to the SPA thermal spring complex, at the entrance to the bathing complex, you can see a copper bathtub used for the carbonated baths.
Pure, laden with the metal that gives it its rusty colour, it is used in carbonated baths in the famous copper bathtubs (a metal that it needed for the chemical reaction with the water) inherited from the old thermal springs.
On entering the bathtub filled with water, the body is instantly covered in thousands of bubbles that caress the skin.
Brush them away…they slowly reform, just a bit smaller.
Slightly sparkling on the surface, the Marie-Henriette confers minute tingling sensations and waves of warm currents within the body.

Very old natural mineral water, located adjacent to faults allowing deep water to be brought to the surface in the form of an emulsion in dissolved gas.
This gas primarily originates from the decomposition of marine carbonates located at great depth.

Its uses
  • Carbonated baths
  • Spa massage showers
  • Power showers
Its characteristics

Naturally sparkling, bicarbonated, iron bearing, manganese bearing

Ca 11 mg/l SiO2 8 mg/l
Mg 6,5 mg/l Fe 15
Na 7 mg/l Mn 0,75 mg/l
K 1 mg/l Dry residue
80 mg/l
Ci 5 mg/l CO2 g/l max 3,8 mg/l
S04 8,5 mg/l
NO3 < 0,2 mg/l pH (degassed water) 6,5
HCO3 70 mg/l rH (degassed water) 16