A valve assembly adapted to move to a valve-closed position upon a push of a valve actuating means, and to a valve-open position upon another push of the valve actuating means, including: • a housing having a first chamber extending from a first open end and a second chamber extending from a second open end, said second chamber being in open communication with the first chamber; • a valve plug, at least a portion of the valve plug is located within the second chamber, and which is adapted to seal the second open end; and • a valve actuating means, at least a portion of which is located within the first chamber, wherein the assembly further comprises a first biasing means acting against pushing of the valve actuating means and adapted to bias the valve actuating means back towards its original position after being pressed by a user, a second biasing means influencing the valve plug to rotate within the second chamber towards the valve actuating means, wherein the valve plug includes a first end, an intermediate section and an aperture sealing end opposed to the first end, wherein the valve actuating means includes a first end located within the second chamber of the housing and an opposed exposed end wherein the aperture sealing end of the valve plug is adapted to seal the second open end of said second chamber and the exposed end of the valve actuation means is adapted to be pushed by a user, characterised in that the valve actuating means includes a plurality of radially extending ribs adjacent said first end and the valve plug includes a plurality of ribs extending radially from the intermediate section, and the second chamber of the housing has an internal surface having channels (64A, 64) adapted to receive the ribs of the valve plug and the ribs of the valve actuation means to constrain the valve plug and the valve actuating means, when pushed to move to the valve-open position, to translate by the ribs moving along said channels and then to allow the valve member to rotate by engagement between surfaces of the valve plug and the valve actuating means under influence of the second biasing means to move to the valve-open position, and to rotate and then translate under influence of the first biasing means when pushed again to move to the valve-closed position, wherein the channels and the ribs of the valve plug are configured so that, when the valve plug moves a predetermined distance along the channels the ribs of the valve plug exit the channels and, under the influence of the second biasing means, the valve plug is caused to rotate within the second chamber; and wherein the valve plug includes a set of inclined surfaces positioned between the first end and the intermediate section of the valve plug, and exposed ends of the ribs of the valve actuating means press against said inclined surfaces under the influence of the second biasing means. • a housing having a first chamber extending from a first open end and a second chamber extending from a second open end, said second chamber being in open communication with the first chamber; • a valve plug, at least a portion of the valve plug is located within the second chamber, and which is adapted to seal the second open end; and • a valve actuating means, at least a portion of which is located within the first chamber, wherein the assembly further comprises a first biasing means acting against pushing of the valve actuating means and adapted to bias the valve actuating means back towards its original position after being pressed by a user, a second biasing means influencing the valve plug to rotate within the second chamber towards the valve actuating means, wherein the valve plug includes a first end, an intermediate section and an aperture sealing end opposed to the first end, wherein the valve actuating means includes a first end located within the second chamber of the housing and an opposed exposed end wherein the aperture sealing end of the valve plug is adapted to seal the second open end of said second chamber and the exposed end of the valve actuation means is adapted to be pushed by a user, characterised in that the valve actuating means includes a plurality of radially extending ribs adjacent said first end and the valve plug includes a plurality of ribs extending radially from the intermediate section, and the second chamber of the housing has an internal surface having channels (64A, 64) adapted to receive the ribs of the valve plug and the ribs of the valve actuation means to constrain the valve plug and the valve actuating means, when pushed to move to the valve-open position, to translate by the ribs moving along said channels and then to allow the valve member to rotate by engagement between surfaces of the valve plug and the valve actuating means under influence of the second biasing means to move to the valve-open position, and to rotate and then translate under influence of the first biasing means when pushed again to move to the valve-closed position, wherein the channels and the ribs of the valve plug are configured so that, when the valve plug moves a predetermined distance along the channels the ribs of the valve plug exit the channels and, under the influence of the second biasing means, the valve plug is caused to rotate within the second chamber; and wherein the valve plug includes a set of inclined surfaces positioned between the first end and the intermediate section of the valve plug, and exposed ends of the ribs of the valve actuating means press against said inclined surfaces under the influence of the second biasing means.