On the sign attached to the outer wall you can read:
This mineral source, taken on October 3, 1882, entered the early 1890s
Possession of the English Government and was called "Johannisbrunnen - King of the
Bottled water "The King of Table Waters" mainly to the English colonies
sent.
Over a hundred workers, mostly women, were taken from the Johannis Fountain
AG employed until the First World War. Thereafter, the marketing of the mineral water
discontinued due to unprofitability of the company Apollinaris in Bad Neuenahr. Until the
1960s could be taken from the cave still spring water. After that, the
Grotte no longer maintained. In 2004 succeeded on initiative of some
Customs houses citizens the environment accessible by regulated drainage of the water again
to restore the grotto and bring it into its present state.
Since the source is no longer controlled by water analysis, there is no longer water to
Consumption approved (no drinking water).