The world's strongest sulfide brine, used for treatment at the Physiotherapy Centre, comes from the “Malina” borehole in Solec-Zdrój. It is classified as highly mineralized chloride-sodium water (brine), sulfide, bromide, iodide and boron water, with the world's highest content of active sulfur compounds.
The effectiveness of balneotherapy depends on the concentration of active sulfur compounds in the water. Using therapeutic waters with high concentrations of sulfur compounds (over 100 mg/1L) provides the best therapeutic results in spa treatment. Like any stimulus therapy, it requires a series of treatments, with effects lasting about a year after treatment ends.
Selected
sulfide waters in Poland
| Spring location | % mineralization | Sulfur compounds: water intake |
| 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 |
