Thermal waters (hot waters)

Geothermally heated groundwaters with a temperature higher than a given value and which erupt or are brought up artificially from underground are called thermal waters or hot waters. Due to the heating effect of geothermal energy the deeper the water derives from the higher its temperature is. (The deeper we go, on average the temperature rises 3°C, but it might vary depending on the geological structure of the place). In Hungary this value is 5-8°C. The thinner crust of the earth and the volcanic activities may raise the temperature.  Due to varied geological features the lower values of the temperature of thermal waters are different from country to country. The lowest value might depend on the area of use as well.  Low values are as follows:

• From a hydrogeological point of view the temperature of thermal water exceeds the value of  the annual mean temperature.  (In Hungary it is cca  10°C);
• From a balneological point of view waters with a temperature above 20°C are considered thermal waters. (General definition in Europe).
• Considering Hungary’s favourable geological features (the higher value of geothermal gradient), in Hungary those waters are considered thermal waters, the temperature of  which  reaches or exceeds  30°C.

The mineral content of the deep layers of the earth’s crust are also dissolved in thermal waters, so they are also considered mineral waters as well in many cases with considerable healing effects. The geothermal energy of thermal waters is used in many ways. (Thermal waters can be used to heat pools, homes, greenhouses, or they can be used to generate energy).

Variations of the word ’hot springs’ (hévíz in Hungarian) may often appear in geographical names. Examples include Galgahévíz (Pest County), Hőlak (a settlement northeast of Trencsén in Slovakia). The town of Tapolca (Veszprém County), Teplice (a town in the Czech Republic) Toplica (a river in Croatia). 

In the northern part of Europe (e.g. in Sweden, Denmark, Holland and Belgium) there are no hot springs with temperatures over 25-30 °C. Even in countries of well established bathing culture, like Germany, Austria, the Czech republic and Slovakia, they are rare, while in Hungary we have got quite many of them. (Bodnár L. 2000).

Medicinal and thermal baths are places for pilgrimages in European health tourism. The best known places include Spa, Budapest, Karlovy Vary, Vichy and Baden. The bathing water erupting from underground at these places can be utilized with the help of different bathing establishments.  „ By European Spa Association statistics the number of annual guest nights spent by a total of 20 million guests is the highest in Germany, Austria, Italy, France and Switzerland. On the other hand new areas and service providers are actively joining health tourism by offering more and more services. Competititon is being very intense in this area. (Sándor R. 2011)”.