Nonnenbach
Location
Country	Germany
State	North Rhine-Westphalia
Reference no.	DE: 271812
Physical characteristics
Source
• location	Dahlem-Schmidtheim
• coordinates	50°24′49″N 6°35′22″E / 50.4136639°N 6.5893417°E / 50.4136639; 6.5893417
• elevation	539 m above sea level (NHN)
Mouth
• location	Ahr near Blankenheim
• coordinates	50°25′27″N 6°40′14″E / 50.4242028°N 6.6705556°E / 50.4242028; 6.6705556
• elevation	407 m above sea level (NHN)
Length	6.992 km [1]
Basin size	10.885 km2 [1]
Basin features
Progression	Ahr→ Rhine→ North Sea
Landmarks	Villages: Nonnenbach

The Nonnenbach is a seven-kilometre-long tributary of the Ahr in the area of Blankenheim in the district of Euskirchen in the German state of North Rhine-Westphalia.

The source of the Nonnenbach lies in woods about 2 kilometres east of Schmidtheim, on the far side of the B 51 and not far from gravel pits already partly filled with groundwater. It flows past the eponymous village and empties into the Ahr a good 2 kilometres south of Blankenheim. Apart from the Seidenbach and the Günzelbach it is also fed during its short course by the streams of numerous gullies, known locally as Seifen.

• Mittlerer Seifen (left)
• Seidenbach (left), 2.0 km
• Günzelbach (left), 1.8 km
• Wallbach (left), 1.8 km

• List of rivers of North Rhine-Westphalia