A separation apparatus for separating mud from water has an input tank device, a pipe device and a first separating assembly. The input tank device has an input tank. The pipe device has a first pipe having a first end and a second end. The first end of the first pipe is connected securely to the input tank. The first separating assembly has a main structure having a hydrocyclone. The hydrocyclone is connected to the second end of the first pipe. Accordingly, the hydrocyclone can efficiently and quickly separate mud from liquid of the raw water in the input tank.