Process water play a very important role within ceramic activities, being involved in a wide range of production’s steps. If on the one hand they are strictly necessary to the course of the work, they can lead on the other hand to problems when they do not fits the required production parameters. The fourth episode of the podcast APPARENTLY INVISIBLE. CHEMISTRY IN CERAMIC, now available on the leading audio platform, is exactly focused on this topic. We talk about electrical conductivity, net and groundwater, waters clarification, sanitization, pH, depuration, tank storage... Which are the most impotant issues?What do we should know to prevent or minimize them?