The mineral waters in the vicinity of Otročín are the northernmost of a Teplá group acidulous springs. There are five mineral springs near the village mentioned while the most famous are the Ovčí (“Lamb”), the Lower and the Upper springs. While the first two has disappeared, the Upper Otročín Mineral Water was in 2008 adjusted and fitted with square wooden gazebo. Its situated on the blue and white marked trail named „Krajem živých vod“ (“Across the Region of Living Waters”).
The spring on the right bank of the Nadlucký Creek is mentioned already in the 17th century by the Czech historian and Jesuit Bohuslav Balbinus. The dating on the hollow trunk catchment bears the year 1819.
The spring rises at some of the smaller tectonic lines penetrating crystalline rocks of the Teplá-Barrandian unit. The sillimanite gneisses with interlayers of coarse-grained amphibolites are predominant.
Cadastre: Otročín
Composition type: cold, weakly mineralized, hydrogencarbonate-calcium-magnesium ferruginous acidulous water
Temperature (°C): 7
Capture dimensions (cm): 50
Capture: hollow trunk
Depth (cm): 65
Content of CO2 (mg/l): 2118
Sea level (m): 675