The water reservoir, located in the northern part of Siedlce Plateau, on the river Cetynia, in the municipality of Sabnie, located on the grounds of the village Niewiadoma, Nieciecz Włościańska, Kupientyn-Kolonia and Kupientyn, about 5 km from Sokołów Podlaski.

Tank was built between 2010 - 2013. The reservoir surface at normal impoundment levels at 42,22 ha, length approx. 3.8 km, the average width of 114 m. The length of coastline is 5.9 km away.