A liquid spray system (1a, 1b, 1c, 1d) comprising: a receptacle for holding liquid, the receptacle comprising: a main body; a reservoir having a liquid outlet; a displacement member moveable within the main body for varying a capacity of the reservoir and having a liquid contacting side and an air contacting side; an air inlet in fluid communication with the air contacting side of the displacement member; a support structure (200a, 200b, 200c, 200d) for supporting the receptacle; a spray applicator comprising: a liquid inlet for receiving liquid from the liquid outlet of the reservoir; a liquid outlet; a liquid outlet valve for controlling the release of liquid via the liquid outlet; a trigger for controlling the outlet valve; and an air pressurising device (400a, 400b, 400d) in fluid communication with the air contacting side of the displacement member and arranged to be operable to move the displacement member, in use; the air pressurising device also being in fluid communication with the liquid outlet valve of the spray applicator and being arranged to be operable to propel liquid out of the liquid outlet valve of the spray applicator, in use, characterised in that: the support structure (200a, 200b, 200c, 200d) comprises an accommodating part for housing the receptacle; the receptacle is a cartridge insertable into the accommodating part the support structure (200a, 200b, 200c, 200d) is wearable or floor-standing, and the spray applicator is holdable by a hand of a user. a receptacle for holding liquid, the receptacle comprising: a main body; a reservoir having a liquid outlet; a displacement member moveable within the main body for varying a capacity of the reservoir and having a liquid contacting side and an air contacting side; an air inlet in fluid communication with the air contacting side of the displacement member; a main body; a reservoir having a liquid outlet; a displacement member moveable within the main body for varying a capacity of the reservoir and having a liquid contacting side and an air contacting side; an air inlet in fluid communication with the air contacting side of the displacement member; a support structure (200a, 200b, 200c, 200d) for supporting the receptacle; a spray applicator comprising: a liquid inlet for receiving liquid from the liquid outlet of the reservoir; a liquid outlet; a liquid outlet valve for controlling the release of liquid via the liquid outlet; a trigger for controlling the outlet valve; and a liquid inlet for receiving liquid from the liquid outlet of the reservoir; a liquid outlet; a liquid outlet valve for controlling the release of liquid via the liquid outlet; a trigger for controlling the outlet valve; and an air pressurising device (400a, 400b, 400d) in fluid communication with the air contacting side of the displacement member and arranged to be operable to move the displacement member, in use; the air pressurising device also being in fluid communication with the liquid outlet valve of the spray applicator and being arranged to be operable to propel liquid out of the liquid outlet valve of the spray applicator, in use, characterised in that: the support structure (200a, 200b, 200c, 200d) comprises an accommodating part for housing the receptacle; the receptacle is a cartridge insertable into the accommodating part the support structure (200a, 200b, 200c, 200d) is wearable or floor-standing, and the spray applicator is holdable by a hand of a user. the support structure (200a, 200b, 200c, 200d) comprises an accommodating part for housing the receptacle; the receptacle is a cartridge insertable into the accommodating part the support structure (200a, 200b, 200c, 200d) is wearable or floor-standing, and the spray applicator is holdable by a hand of a user.