Brenztopf, Karst spring in Königsbronn, Germany.

Brenztopf is a karst spring at the foot of the Herwartstein rock in southern Königsbronn, next to the town hall and near the railway station. Its water rises from an opening several metres deep in a pool up to 4.3 m deep, fed through fissures and cavities in the White Jurassic mass limestone. The outflow forms the Brenz, a Danube tributary, and the spring is a geotope of the UNESCO Geopark Swabian Alb.

The spring has been dammed for centuries; its water powered an iron hammer works. Since 1890 the water has driven turbines for electricity, today a Kaplan turbine. The area at the spring and behind the Hammerschmiede was redesigned in 2010.

The spring's water has powered a hammer forge for centuries, and since 1890 it has generated electricity, today via a Kaplan turbine. The pool area and the space behind the Hammerschmiede were redesigned in 2010. The Brenztopf is the start and end point of the Königsbronn route of the Karstquellenweg, a marked trail linking karst springs of the Swabian Alb.

The spring sits near the town center and is easily accessible from walking trails in the area. Viewing platforms allow visitors to see the water up close without obstacles or difficult terrain.

The spring's discharge ranges from 230 to over 20,000 litres per second, averaging 1,270 l/s, making it one of Germany's strongest springs. Its catchment area reaches as far as Irmannsweiler, Bartholomä, Amalienhof and Zang in the northern Albuch.