The Vacha ( ) is a river in south Bulgaria, one of the main right tributaries of the Maritsa. It is 105 km long and is formed by the confluence of the Shirokolashka reka and the Byunovska reka. The river passes through Krichim Dam and Vacha Dam that secure drinking water for Plovdiv and its plains. The Vacha runs through the Rhodopes forming a deep valley where the two dams are located. An important town in the valley is Devin.
It is the second largest river that has its source in the Rhodopes after the Arda. The Vacha does not flow close to any industrial enterprises, which is the reason for its clear water. The origin of its valley is similar to that of the Chepelare River.