This paper details the results of fieldwork research on the effect of pipe fittings on particle accumulation in a drinking water network (DWN). The term, affected section of pipe fitting (ASPF) is introduced, which is the length of pipe beyond the pipe fitting where the temporal deposition/erosion processes of particles, due to the daily hydraulics, leads to higher concentrations of particles on the pipe walls. The lengths of the ASPF were calculated to be 5.31– 299.40 m. In order to quantify the mass of particles washed out of fire-hydrants, the resuspension potential method (RPM) or uni-directional flushing (UDF) program, were performed on four different DWNs (populations <10 000–700 000; network length: 20–1374 km; DN 100 – DN 250 mm). The flow and turbidity during flushing was measured with online instruments. A relation was found between the concentration of total solids (TS) analysed from grab samples and the turbidity measured with online equipment: 1 NTU = 0.303 mg/l (n = 63). The turbidity potential of accumulated particles for the ASPF was suggested as coefficient (J) and varied from 1.02–3.74. The total mass of particles accumulated in either the ASPF or straight sections varied from 0.57– 7.14 g/m (n = 24) and 0.46–5.79 g/m (n = 21), respectively. Therefore, pipe fittings have greater amounts of dry mass compared with straight sections of pipe, which can be explained by the inertial effects of pipe fittings.