The Faulbrunnen is a little way away from Wiesbaden's other springs. The thermal water is mixed with groundwater here, making it the coldest spring. The water is just 14 degrees Celsius when it reaches the surface.
The name comes from the previously foul taste of the water due to the hydrogen sulphide dissolved in it. This substance was formed by bacteria from the iron sulphide that is dissolved in the mineral water. When the fountain was renovated in the 1960s, the well was clad with clay, so that the bacteria were no longer able to come into contact with the water and the formation of foul-smelling hydrogen sulphide was largely stopped.
The water of the Faulbrunnen is said to have a positive effect on the liver, gall bladder and intestine, making it suitable for drinking treatments. Platz der Deutschen Einheit is currently being redesigned and the drinking fountain has been temporarily removed.