A system for proportioning and dispensing concentrated liquid products is disclosed. The components of the system's first embodiment are mounted upon a cart (12). A concentrate solution tube (14) is interconnected to a dilution assembly (61) containing an aspirator (26). A water supply assembly (69), containing a valve (75) and backflow preventer (74), is connected to the aspirator assembly (26) when dilution of the concentrated product (13) is desired. A discharge tube (68) carries the diluted product from the aspirator assembly (26) to a container (60). The system's second embodiment has a spray gun assembly (150) containing an aspirator (167), a valve (166), and preferably though not necessarily, a backflow preventer (165). The concentrate pickup tube (114) attaches to the spray gun assembly (150) with a releasable connector (170). The spray gun assembly has a rigid delivery tube (153) for dispensing to large containers (160), and a nozzle tip (180) for attachment to an inlet port (119) of a jug (111). Also disclosed is a method for dispensing and handling solutions.