An ink supply system for an ink jet printer, particularly a continuous ink jet printer, has a manifold assembly of two parts that are brought together at interfacing surfaces. At least one of the surfaces has a plurality of ink flow channels for conveying ink around an ink circuit between components. The other of the interfacing surfaces is configured to close and seal the channels. A plurality of ports is provided in fluid communication with the channels, the circuit components being connectable to the ports. The manifold assembly provides for a compact and neat arrangement free of many tubes and pipes. The lower number of connections significantly reduces the risk of leakage.