濁水溪
Ershui is bordered on the north by Tianzhong Township, to the east by Mingjian Township in Nantou County, and to the west by Xizhou Township. Its name means, literally, "Two Waters", which is a reference to the two irrigation canals constructed in the township, 1 and 2, linking the waters from the nearby Zhuoshui River to the fertile Changhua Plain. Ershui is known for its picturesque scenery and the nearby Bagua Mountain Range, and offers many biking and hiking trails. The bulk of Ershui's population lives near its central plaza in front of the Ershui railway station, on the Western Line on the TRA's railway network.