Every thermal bath in Europe describes its water in the warmest words its language allows. Healing, curative, therapeutic, restorative. Most of those words are free: nobody grants them, nobody checks them, and a marketing agency can write them into a page in an afternoon.
A few words are not free. Gyógyvíz in Hungary, Heilwasser in Germany, água mineromedicinal in Portugal — these are legal designations. A national authority takes samples, runs an analysis, decides whether the composition is stable and whether it meets a defined standard, and then permits the term. Where the designation exists, using it without permission is not puffery but a breach.
This article is about the baths that hold one. There are 208 of them in this catalogue: 207 thermal baths and a single spring, out of 992 thermal baths in total. Roughly one bath in five.
Where they are, and who says so
The interesting column in the table below is not the first one. It is the second — whether we read the designation off a state register or off the operator's own website.
| Country | Certified | From a state register | Has a website | Publishes a water temperature |
|---|---|---|---|---|
| Hungary | 106 | 30 | 95 | 22 |
| Germany | 51 | 0 | 51 | 24 |
| Portugal | 42 | 40 | 17 | 0 |
| Austria | 7 | 0 | 7 | 4 |
| Switzerland | 1 | 0 | 1 | 1 |
| Italy | 1 | 0 | 1 | 0 |
Read the Portuguese row and the German row against each other, because between them they describe two entirely different worlds.
Portugal is a register with barely a website. Forty of its 42 designations come straight from the Direção-Geral de Energia e Geologia, the state body that holds the concessions for mineral-medicinal water. The Portuguese state knows exactly what is in the water at Termas de Moura, Termas da Curia, Termas do Luso, Termas das Caldas de Aregos — and not one of those four has a website. Twenty-five of the 42 have no website at all, only one states what the water is used for, and not a single one publishes a pool temperature. These are old spa towns with a state file and no marketing department.
Germany is 51 websites and no register. Every German bath here declares Heilwasser on its own pages, half of them publish a temperature, and 28 say what the water is for. But the figure in the register column is zero, and that zero is about us rather than about Germany: the registers we have imported are Hungary's and Portugal's. Germany's designation is real and granted under national medicines law — we simply have not yet read the authority's own list, only the operators' accounts of it. A blank in a table is sometimes a fact about the world and sometimes a fact about the person who made the table, and it is worth being told which.
Hungary sits between the two, and is the only country where the same bath is often documented twice: 30 matched against the national public health register, 95 with a working website, 47 stating indications. Hungarian bathing culture assumes a public that reads these things.
What the designation actually attests
A certificate is a statement about water, not about people. It says the spring has been sampled, that its composition is known and stable, and that the composition meets a threshold — a mineral content, a particular constituent, sometimes a temperature at the wellhead. It does not say the water treats anything, and no authority in Europe claims that it does.
This distinction survives in the paperwork and dissolves in the marketing. A bath with a genuine designation will often set it beside a list of conditions its water is "used for", and the two things sit in the same paragraph as though the state had endorsed the list. It has not. It endorsed the analysis.
What is in the water
Of the 208, only 82 name a dominant constituent at all. Among those that do:
| Constituent | Baths |
|---|---|
| Sulphur | 34 |
| Sodium | 33 |
| Hydrogencarbonate | 29 |
| Fluoride | 24 |
| Iron | 24 |
| Chloride | 22 |
| Iodine | 19 |
| Calcium | 16 |
| Magnesium | 14 |
| Radon | 2 |
Radon is the outlier worth naming, because there are only two: Alpentherme Gastein in Austria and Therme Meran in South Tyrol. Gastein built an entire tradition on it.
Fourteen baths publish a total mineralisation figure — the single number that would let you compare one water against another — and the spread among them is enormous. Naturtherme Bedernau in Bavaria publishes 594 mg per litre, which is ordinary mineral water. Bükkszéki Gyógy- és Strandfürdő in Hungary publishes 22,989, which is brine, nearly forty times as concentrated. Fackelmann-Therme Hersbruck sits at 14,200 and Hajdúnánás Gyógyfürdő at 7,981. Two waters can both be certified medicinal and have almost nothing chemically in common.
What they say it is used for
Eighty-one of the 208 state indications. Joints and backs dominate, as they do across the whole catalogue: 62 name musculoskeletal complaints, 32 rheumatic conditions specifically, 28 circulatory, 21 skin, 19 recovery after injury, 16 gynaecological, 6 respiratory, 4 digestive. Every one of those is the operator's statement, reported here as theirs.
Temperature, and one number not to trust
Fifty-one publish a pool temperature. The median is 37 °C — body temperature, which is where thermal water stops registering as hot or cold and simply stops registering. The warmest is Nagyatádi Termál Strandfürdő in Hungary at 42 °C.
The lowest figure in the set is 20 °C, at Alpentherme Gastein, and we do not believe it describes the thermal pool. A large spa publishes many temperatures — cold plunge, outdoor basin, children's pool — and a single figure lifted from such a page is the weakest kind of fact this catalogue holds. We would rather show you the number and tell you we distrust it than quietly drop it.
How to check a claim yourself
- Look for the legal term, not the adjective. Gyógyvíz, Heilwasser, água mineromedicinal, léčivá voda are granted. "Healing", "curative" and "wellness" are self-applied.
- Ask who granted it and when. A bath that holds a designation can name the authority. One that cannot name an authority is describing itself.
- Look for the analysis, not the summary. The document lists constituents in milligrams per litre and carries a sampling date. A page that names one mineral in a headline and shows no figures has told you almost nothing.
- Separate the certificate from the indication list. The authority approved the composition. The list of conditions beside it is the operator's, however official the layout looks.
- Check the date on everything. Compositions change slowly and web pages change slower. An analysis from 2004 on a page last touched in 2011 is still a real analysis, but you are reading history.
What this article cannot tell you
Whether certified water does anything for you. A designation is evidence that a state tested a spring and found what it expected to find. It is not evidence about a body, and the research literature on balneotherapy is genuinely unsettled — not a thing this catalogue can adjudicate by counting baths.
What we can tell you is who holds a designation, which of those we verified against a state register rather than a brochure, what their analyses contain where they publish them, and how much of it is missing. On the last point the honest summary is blunt: of 208 certified baths, 126 do not name a single constituent, 127 do not say what the water is used for, and 194 publish no mineralisation figure at all. The certificate exists. The document behind it is usually not on the internet.