Cleaning, conversion coating, and electrocoating are typical wet-chemical process units in high-volume painting plants for car bodies. These surface treatment processes must meet ever higher demands in terms of quality, cost savings, and environmental compatibility. Besides the efficient use of energy, the conservation of water resources plays a key role, for which both the integration of existing and the development of new technologies for process bath care are essential core elements. This article discusses the use of various state-of-the-art technologies.