Every 24 hrs 750,000 litres of water flow into the Lake Ørnsø. The rich water flow of the Spring Arnakkekilden was a contributing factor, when a group of doctors and locals managed to create the basis of a water based and health-giving health-resort on this very site in 1883.

In the middle of the 19th century, medical science had growing interest in exploiting ferrous water as a healing and preventative measure against ailments. During the 1870s, it was discovered that the water from the Spring Arnakkekilden was particularly rich in minerals and iron.

Taste the cold water
At their leisure guests in the park can taste the water flowing from the well. They will also note the temperature of the water, which is constant and chilly 7° degrees centigrade. In spite of the reddish appearance of the spring water, the water is drinkable. It has a special taste, and it is high on minerals like iron, calcium and sodium. The iron is clearly visible because it precipitates ochre, colouring the surroundings reddish-brown.

A historic facility
The facility around the source of the spring is from 1929, when it was established by the Friends of Silkeborg Bad. Little has changed over the years. Around the millennium, time had taken its toll on bulwark and basin walls. Therefore the Art Centre Silkeborg Bad initiated a collection and fundraising to renew the facility. This succeeded with support from local contributors, private funds, the municipality of Silkeborg and the Realdania Foundation. A thorough renovation was carried out during 2006-2007.

The Art Centre indoors exhibition has a small presentation of the hundred year-old history of the facility as a health-resort, including old pictures of the Spring Arnakkekilden.

The modern facility
Today the facility has an appearance that respects the original to a wide extent.  It has an upper pool, a drinking well and "water stairs" to lead the water to a lower pool. In the original form, this basin was closed against the Ørnsø lake by a small wooden bridge. During the renovation work, it was replaced with a stringent formed bridge to be in harmony with the rest of the facility and to be more solid.  

Bottling of spa water
Since the 1880s, it has been possible to enjoy the mineral-rich water from Arnakkekilden. First bottled and sold P.O. Long from Silkeborg well water under names like ‘Silkeborg Iron Water’ or ‘Silkeborg Iron Water with carbon dioxide’. From 1968, it was Silkeborg's local brewery, Neptun, that bottled the well's water and sold it as bottled spa water. Neptune bottled since on behalf of Carlsberg, which has bottled and sold spa water from Arnakkeilden until the end of 2020.