A fluid dispenser and method of operating the same. The fluid dispenser can include a wheel driven by diluent passing along a flow path in the fluid dispenser. The wheel can be connected to a pump to pump fluid from a reservoir for dispense into the diluent. In some embodiments, the ratio of wheel rotations to pump cycles is selected to provide a desired and repeatable dilution ratio of concentrated fluid to diluent. The fluid dispenser can be portable and/or disposable, and in some embodiments is adapted for installation on an upper rim of a reservoir wall. Also, the fluid dispenser can be provided with a baffle limiting the velocity and impact of incoming diluent to the wheel driving the pump, thereby improving dosing accuracy of the dispenser in some embodiments.