Abstract: A closed-loop heat exchanger pipework cleaning apparatus includes a water conditioning apparatus and a pipework conditioning apparatus. The water conditioning apparatus is adapted to receive water and to remove particulate contaminants from the water and to kill microorganisms in the water, to produce conditioned water, and to deliver the conditioned water into a closed-loop pipework system of a heat exchanger until the closed-loop pipework system is substantially full of water. The pipework conditioning apparatus is adapted to receive a proportion of the water circulating through the closed-loop pipework system and to remove further particulate contaminants from the water to produce cleaned water, and to return the cleaned water into the closed-loop pipework system.