An adapter for use with an air/water tip (e.g., a three-way dental syringe). The adapter comprises a body including a proximal end and a distal end, a mixing chamber disposed between the proximal and distal ends, a water delivery lumen for delivering water from a coupleable fluid dispensing device to the mixing chamber, and a separate air delivery lumen for delivering air from a coupleable fluid dispensing device to the mixing chamber. The cross-sectional area of the water delivery lumen at a location adjacent the mixing chamber is greater than the cross-sectional area of the air delivery lumen at a location adjacent the mixing chamber. The relative cross-sectional areas act to balance pressures of air and water entering the mixing chamber so as to provide a ratio of volumetric flow rate of water to air that is between about 0.5:1 to about 2:1.