The world's strongest sulphide brine, used for treatment at the Physiotherapy Centre, comes from the “Malina” borehole in Solec Zdrój. It is classified as highly mineralised chloride-sodium water (brine), sulphide, bromide, iodide and boric, with the world's highest content of active sulphur compounds.
The effects of balneological treatments depend on the concentration of active sulphur compounds in the water. Using medicinal water sources with high concentrations (over 100 mg/1L) of sulphur compounds ensures the best therapeutic effects in spa treatment. Like any stimulus therapy, it requires a series of treatments, and the therapeutic effects last about a year after treatment ends.
List of selected
sulphide waters in Poland
| Spring location | % mineralisation | sulphur compounds in water |
| Swoszowice | 2.64% | 70.04 mg H2S/1L |
| Krzeszowice | 0.28% | 6.00 mg H2S/1L |
| Horyniec | 0.75% | 23.00 mg H2S/1L |
| Busko-Zdrój | 1.40% | 50.00 mg H2S/1L |
| Solec-Zdrój "Malina" | 3.10% | 830 mg H2S/1L |
