Detection device for detecting a flow of liquid in a household appliance; said detection device being intended for being connected to and/or integrated with a pump; said detection device comprising a flow meter in turn including: - a hollow casing internally having a cavity configured to be crossed by said flow of liquid and defined by a supporting half-shell having at least one inlet configured to receive said flow of liquid in said cavity, and a closing element sealingly coupled with said supporting half-shell and having at least one outlet configured to deliver said flow of liquid outside said cavity; - an impeller rotatably supported by said hollow casing in said cavity and configured to be rotatably driven by said flow of liquid around an axis of rotation (X-X), and - detection means configured to detect a rotation of the impeller and output a flow signal indicative of the rate of said flow of liquid as a function of said rotation of the impeller; and wherein said at least one outlet is radially spaced apart from the axis of rotation (X-X) of said impeller; wherein said hollow casing further comprises an additional supporting half-shell sealingly coupled to the supporting half-shell; wherein said hollow casing also has a chamber defined by said additional supporting half-shell and by the closing element; wherein said at least one outlet consists of at least one through hole formed in said closing element; characterized in that said additional supporting half-shell comprises a central outlet portion that allows said flow of liquid to exit the chamber which has an annular shape and is situated around the central outlet portion. - a hollow casing internally having a cavity configured to be crossed by said flow of liquid and defined by a supporting half-shell having at least one inlet configured to receive said flow of liquid in said cavity, and a closing element sealingly coupled with said supporting half-shell and having at least one outlet configured to deliver said flow of liquid outside said cavity; a supporting half-shell having at least one inlet configured to receive said flow of liquid in said cavity, and a closing element sealingly coupled with said supporting half-shell and having at least one outlet configured to deliver said flow of liquid outside said cavity; - an impeller rotatably supported by said hollow casing in said cavity and configured to be rotatably driven by said flow of liquid around an axis of rotation (X-X), and - detection means configured to detect a rotation of the impeller and output a flow signal indicative of the rate of said flow of liquid as a function of said rotation of the impeller; and wherein said at least one outlet is radially spaced apart from the axis of rotation (X-X) of said impeller; wherein said hollow casing further comprises an additional supporting half-shell sealingly coupled to the supporting half-shell; wherein said hollow casing also has a chamber defined by said additional supporting half-shell and by the closing element; wherein said at least one outlet consists of at least one through hole formed in said closing element; characterized in that said additional supporting half-shell comprises a central outlet portion that allows said flow of liquid to exit the chamber which has an annular shape and is situated around the central outlet portion. wherein said at least one outlet is radially spaced apart from the axis of rotation (X-X) of said impeller; wherein said hollow casing further comprises an additional supporting half-shell sealingly coupled to the supporting half-shell; wherein said hollow casing also has a chamber defined by said additional supporting half-shell and by the closing element; wherein said at least one outlet consists of at least one through hole formed in said closing element; characterized in that said additional supporting half-shell comprises a central outlet portion that allows said flow of liquid to exit the chamber which has an annular shape and is situated around the central outlet portion.