This paper analyses the utilization of water and recycled fiber from waste paper for the production in one Serbian cardboard mill. Water and fiber consumption, wastewater generation and its characteristics, as well as sludge recirculation were monitored during production of various paper types, with different grade and weight. The aim was to evaluate production rationality and running stability concerning water and fiber utilization and possibilities for their conservation. Cleaner production measures inside the mill and in the effluent treatment plant were suggested for the improvement of wastewater quality and water conservation. Savings in water and fibers were estimated, with the respect to economic and environmental aspects of proposed cleaner production measures.