The Hasborner Sauerbrunnen is located directly on the banks of the Sammetbach stream on the "Zwei-Bäche-Pfad" (two stream path) and is a spring that emerges and is captured in Devonian rocks. The spring water is brown in colour and tastes sour. Dissolved iron is responsible for the colouring and carbon dioxide of volcanic origin for the taste. The surroundings of the acidulous well are ideal for a trip with children, who can play wonderfully in the splashing Sammetbach. A ladle hangs in the fountain for tasting the water.