Abstract: A bulk ink delivery system for ink jet printers and the like includes one or more cartridge housings which conform to the shape of a manufacturer's standard, ink-filled cartridge so that the cartridge housing may be substituted for the ink-filled cartridge normally associated with the printer. Inside the housing is situated an ink pump, a reservoir, and a control circuit for operating the ink pump. The ink pump replenishes the ink reservoir in the cartridge housing, and receives ink from one of several external ink bottles, one bottle for each color and one bottle for each cartridge housing. The control circuit for operating the pump includes a high volume primary level sensing switch, which monitors the quantity of ink in the internal reservoir within the cartridge housing. The control circuit energizes or de-energizes the pump to add more ink as required to the reservoir in order to maintain a pre-determined level of ink within the reservoir.