In combination with a pressurized feed water supplied reverse osmosis cartridge that has a purified water outlet and a reject water outlet;
- a tank that has a movable barrier therein that subdivides an interior of said tank into first and second compartments of variable volume and that are in communication with, a purified water passage and a reject water passage defined in said tank, said purified water passage in communication with said purified water outlet;
- a purified water dispensing and reject water control device, said control device including:
- (a) an elongated vertical valve body that has upper and lower ends and a hollow interior defined in part by means defining upper and lower confined spaces that include upper and lower valve seats and said valve body including a purified water inlet in communication with said upper confined space and said purified water passage;
- a reject water inlet in communication with said reject water outlet;
- said reject water passage in communication with said lower confined space and said second compartment;
- said elongate valve body having formed therein a reject water receiving cavity adjacent said upper end of said valve body;
- a reject water drain outlet situated below said cavity;
- (b) first and second valve members which when in first positions seal with said upper and lower valve seats, said second valve member including a first water flow restrictor through which reject water may flow upwardly from said lower confined space when said second valve member is in said first position;
- (c) first means that tend to maintain said first and second valve members in said first position;
- (d) a tube and elongate tubular member longitudinally, and concentrically disposed in said valve body, said tube disposed in a fixed position in said valve body, said tubular member having an upper end disposed above said reject water receiving cavity and a lower end within said lower confined space, said elongate tubular member, longitudinally movable relative to said tube, said tubular member having a first elongate passage therein of sufficiently small transverse cross section as to serve as a second reject water flow restrictor, said tubular member and tube cooperating to define a second passage therebetween that is in communication with said upper valve seat and a purified water dispensing outlet in said upper end of said valve body, and said tube and a portion of said valve body most adjacent thereto cooperating to define a third passage that is in communication with said reject water receiving cavity and said reject water drain outlet, said elongate member so operatively associated with said first and second valve members that said first and second valve members are moved to second positions when said elongate member is moved downwardly from a first to a second position relative to said tube, said second valve member when in said second position permitting reject water entering said lower confined space to by-pass said first flow restrictor and substantially by-pass said second flow restrictor to flow through said reject water passage to said second compartment to expand said second compartment and force purified water in said first compartment to flow therefrom through said purified water passage, purified water inlet, and second passage to discharge through said purified water dispensing outlet so long as said first and second valve members are in said second positions, with flow of purified water from said purified water dispensing outlet and flow of reject water to said second compartment terminating when said first and second valve members return to said first positions, with purified water from said purified water outlet thereafter flowing to said first compartment to expand said first compartment and force reject water in said second compartment therefrom to flow into said reject water passage, into said valve body to enter said second flow restrictor and drop by gravity from said upper end of said tubular member through an air gap into said reject water receiving cavity, and reject water from said reject water outlet entering said lower confined space to flow sequentially through said first and second reject water flow restrictors to said reject water receiving cavity for subsequent flow to said reject water drain outlet.