Prior to the new edition of the ATV-DVWK-A 110  in 1988, planners assumed that the required shear force of the wastewater is guaranteed if, at partial filling, flow velocity of 0.5 m / s and at full charge of at least 1.0 m / s is achieved. On this basis, and the investigations of Karakassonis, the minimum slope used in practice was determined using the Faust equation I_crit = 1000/DN (Circular pipe with half to full filling τ₀=2,5 N/m²) [ATVA110:2001] [Karak1936].