The change in water quality in small water systems is strongly affected by sediment particles. Their transport, deposition and re-suspension due to variability in water demand has a significant impact on the change in water quality. Two significant mechanism of deposit transport and deposition i.e. turbophoresis and turbulent diffusion have been described in the literature. The paper presents the mechanisms of turbophoresis and turbulent diffusion. These phenomena have an impact on the quality of water in small water systems. The aim of the study is to propose procedures of identifying areas of mechanism of particle movement and their accumulation in small water system networks. Simulation of the flow of small water-pipe network at Niewiesz was used for the study. That water pipeline is situated in the central Poland. Many rural areas in Poland have a similar architecture. Modeling of movement of contaminant in close wall areas in pipelines is presented. The article presents the discussion concerning the areas where the mechanisms of turbophoresis and turbulent diffusion occur in the transport of solid particles in water supply systems. The relations between deposition and transporting of particles in turbulent flows depend on a number of parameters, including: particle size, localization of particles in the pipe (at given time), as well as the turbulence of flow. These parameters change depending on the water demand. The type of these changes depends on pipe diameters, material from which the pipes and the fittings are made, water demand and initial quality of water.