It originates from the hills of Achankovil in the Patanamthitta and flows through Mavelikkara, Thiruvalla and Karthikapally Taluk into the left of river Pamba near the Vembanattu Lake. The Anchankovil enriches the Pathanamthitta district of Kerala state. It joins with the Pamba River at Veeyapuram, in the Alappuzha district of Kerala. . Achan Kovil means the shrine of Achan or the supreme deity.The Malayalam words Achan, Appan, Aliyan etc. have Sramana and Buddhist origins. The famous place Pandalam, the native place of Lord Ayyappa is in the banks is this river . Achankovil is also the name of the forest area, which is the catchment area for this river, and of a small town situated in the Achenkovil forest area. The river also passes through the village Vazhuvadi. The River Achankovil nurtures numerous townships on its fertile banks. Among them is Pathanamthitta Town, which is the capital of the Pathanamthitta district. It derives its name from its association with the river; Pathanamthitta, from the Malayalam words Pathanam and thitta, means "houses by the riverside". A Siva Temple called as Kandiyoor Mahadeva temple is also situated on the river banks. This temple which is around 2200 years old is made of black stones. The famous Chettikulangara temple is also near to this.