Disclosed is a reversing valve. The reversing valve controls the position change of a valve element thereof under the joint action of the total changing pressure from a piston side thereof and a compression spring side thereof to make connection and disconnection between different chambers in the reversing valve, so that the reversing valve can control connection and disconnection of relevant waterways. The reversing valve adopts a purely mechanical design and has characteristics of high reliability and fast switching. Also disclosed is a household water purifier including the reversing valve.