There are several sulphur springs in the center of Bad Tennstedt. In combination with microbacteria, hydrogen sulphide forms in the groundwater that flows through layers of peat. The town's main spring can be found in what is now Bad Tennstedt's spa gardens and bears the characteristic name „Stinking Newt“. An investigation in 1991 revealed that the sulphur spring is one of the strongest sulphur springs in Germany with a total content of 21.3 mg hydrogen sulphide.

The water also contains traces of iron and manganese and a high proportion of hydrogen carbonate. Since the discovery of the sulphur spring in 1811, the healing waters of the sulphur spring were only used by private and spa patients until 1990.

The water of the „Stinking Newt“ is made available to patients of the Median Clinic as well as locals and guests in the treading pool in the spa gardens as part of rehabilitation measures.