A water purifier includes a water purification unit, and an ice making unit. The water purification unit includes: a water filter for filtering introduced raw water to provide the purified water and unfiltered living water; a purified water tank including a first storage for storing unfiltered water, a second storage for storing the purified water discharged from the water filter, and a separation membrane formed of an impermeable material which independently partitions the first storage and the second storage and has elasticity, wherein the second storage shrinks when the first storage expands, and the first storage shrinks when the second storage expands; a flow channel connecting the water filter, the purified water tank, and the ice making unit to provide a passage through which the raw water, the living water, and the purified water flow; and a valve unit including a plurality of valve modules.