Apparatus for delivering a fluid, especially for delivering colourants or the like to a premixer stage of plastics forming equipment, for example an injection moulder of extruder is described. The apparatus includes a fluid supply means (200) connected to a reservoir (208) which is arranged to concertina between minimum and maximum volume conditions. The reservoir (208) is connected via pipeline (24) and peristaltic pump (26) to a delivery means which is arranged to deliver the fluid to a desired location. In normal operation, fluid supply means (200) supplies fluid into reservoir (208). When however the fluid supply means (200) is empty, the level of fluid in the reservoir (208) will fall below the level of a capacitance sensor (32) which will sense the presence of air and cause a signal to be output to alert an operator to change fluid supply means (4). The fluid supply means may be changed before the reservoir is empty of fluid and, accordingly, the process may be operated continuously, even during the replacement of a reservoir (4). After replacement of a fluid supply means (4), the reservoir (208) is moved towards its minimum volume, to expel air into the fluid supply means (4), so that the reservoir (208) can be filled with fluid from the reservoir and there is substantially no air in the reservoir to become entrained with fluid as it passes via peristaltic pump (26) to adesired location.