Abstract: Device for a mixer tap comprising a substantially tubular central body (15), inside which there is a mixer assembly (21), a first pipe (16) to feed the cold water, a second pipe (17) to feed the hot water and an outlet pipe (19) for the water, a substantially cylindrical connection element (25) being housed inside the central body (15) arranged between the mixer assembly (21) and the water feeder pipes (16, 17) and water outlet pipe (19), means (26, 27, 30) being provided in the said connection element (25) to house at least a non-return valve (35) or a vacuum breaker valve (36).