An ink reservoir (10) for an ink recirculating system for supplying ink to an inkjet printhead (14) comprises a first chamber (16) for receiving ink from a main ink supply (12) and having a printhead outlet (24) for supplying ink to a printhead (14); and a second chamber (18) in fluid communication with the first chamber for receiving ink from the first chamber in excess of a predetermined height in the first chamber determined by the position of a transfer outlet (20), the second chamber having a printhead inlet (30) for receiving ink recirculated from the printhead and having a return outlet (40) for returning to the main ink (12) supply ink in excess of a predetermined height in the second chamber determined by the position of the return outlet (40), the transfer outlet (20), in use, being vertically above the return outlet (40). In use of the reservoir, because the transfer outlet (20) of the first chamber is vertically above the return outlet (40) of the second chamber, this produces a pressure differential that causes flow of ink from the first chamber (16) to the printhead (14) via the printhead outlet (24), through the printhead (14), with unused ink returned to the second chamber (18) via the printhead inlet (30). The unused ink is then returned to the main supply (12) for reuse, thus circulating surplus ink through the system. The arrangement thus uses gravity to produce the ink flow through the printhead (14), without the need for pumps, level sensors, valves etc. The ink reservoir is self-regulating, with the ink heights in the first and second chambers, and hence the pressure differential, determined by the relative heights of the two outlets.