The Liwiec (or Liw, pronounced or ) is a river in Poland, and a tributary of the Bug River.
The Liwiec flows in the plains of Southern Podlaskie Voivodeship and central Masovian Voivodeship. It is 142 kilometres long and drains 2,763 square kilometres of watershed.
The source of the Liwiec is located to the north-west of MiÃÂdzyrzec Podlaski near Siedlce and crosses Wyszków, Liw, WÃÂgrów, and Stara Wieà Â.
Its lower estuary and confluence with the Bug River is located near the towns of Wyszków and Kamieà Âczyk.
It has a Natura 2000 EU Special Protection Area region.