The present invention relates to three-position faucet for water supply systems, formed by a body (1) housing a ball (3) that can rotate in order to establish positions for opening and closing the passage through the faucet, the ball (3) having a side conduit (14) communicating with another perpendicular downward-oriented conduit (15), whereas another conduit (16) or a smaller diameter extends from a perpendicular side area to the conduit (14), such that the conduit (15) is facing as outlet conduit (6), whereas depending on the rotation of the ball (3), the conduit (14), the conduit (16) or the blind portion opposite any of them can be arranged facing an inlet conduit defined by a tubular bushing (5), for establishing different passage positions or for closing the faucet.