Abstract: A liquid proportioning system constructed according to the principles of the present invention mixes a primary liquid with liquid additive from at least one liquid additive reservoir. The system includes a manifold in which the primary liquid and the liquid additive are mixed. The manifold has an outlet for discharging the mixture, a first inlet for receiving the primary liquid and a second inlet for receiving liquid additive. A plurality of conduits each carry the liquid additive to the manifold from the liquid additive reservoir. Each conduit delivers the liquid additive to the manifold at a different rate under substantially the same operating conditions so that the connection of each conduit to the second inlet results in a different predetermined mixing proportion. Quick connect couplings connect each conduit to the second inlet of the manifold so that the conduits may be quickly connected to and disconnected from the second inlet to change the mixing proportion.