A water mode detection method includes: operating a normal touch detection operation on each of a plurality of touch detection unit groups during each of a plurality of normal scan periods to obtain a first detection result; operating a dummy touch detection operation on a first touch detection group of the touch detection unit groups to obtain a second detection result during a dummy scan period, and setting a common voltage of a second touch detection group of a plurality of non-scanned touch detection unit groups to a reference ground during the dummy touch detection operation; and generating a water mode detection result according to the first detection result and the second detection result.