Virtual tour, you can move through the image with the mouse.

Altstraßbach SourceHigh CO2 content poses danger

The source on the Altstraßbach was found in the 1940s during construction work for the West Wall. It is moderately mineralized, but has an extremely high CO2 content of 3500 milligrams per liter. This makes them particularly dangerous.


  • Coordinates: 50°16.177’N, 6°44.452’E
  • Municipality/location: Walsdorf-Zilsdorf
  • Altitude: 557 m above sea level
  • Water temp: 6.0 °C to 11.0 °C

  • Leute an der Altbachstraßquelle © Natur- und Geopark Vulkaneifel GmbH, Kappest
  • Altbachstraßquelle © Natur- und Geopark Vulkaneifel GmbH, Kappest

This is a Mofetten spring: The water circulating in the loosening zone and some fissures only has a short residence time and is pushed upwards in the spring area. Direct access to the spring bunker is closed by a door for security reasons. When there is little air movement, an invisible CO2 layer up to 20 cm high collects on the bottom of the bunker.

Please be careful!

Animals and people who come too close to this area are at risk of death if they inhale the gas! Caution is particularly advised with dogs and children who have fallen. It only takes a few breaths to die. Even outside the walls, visitors should do the CO2 test with a candle or lighter: if the flame goes out, the CO2 concentration is very high.

Highlights nearby

Hiking trails

We would be delighted if you liked our hiking routes and tour suggestions. Spread the word: The Vulkaneifel is a worthwhile destination!

Guided tours


B421 towards Zilsdorf, in Zilsdorf turn onto Talstraße, the source is on the left opposite the wind turbines.


We use cookies on our website. Some of them are essential for the operation of the site, while others help us to improve this site and the user experience (tracking cookies). You can decide for yourself whether you want to allow cookies or not. Please note that if you reject them, you may not be able to use all the functionalities of the site.