The paper presents research results on rheological properties of a precipitated waterwork sludge. The water content of the sludge studied varied from 100 to 85 per cent at temperatures of 273-293 K, respectively. The sludge in question can be classified as a plastic-viscous fluid, described by the Bingham model. Some empirical relations describing the influence of the water content on tau(O) and eta(pl) have been found. The mentioned parameters were also affected by temperature. The paper describes in detail, technical applications such as the flow of sludge in pipes, as well the flow along the bottom of sedimentation tanks. (C) 1997 IAWQ. Published by Elsevier Science Ltd.