ABSTRACT The continuous steel casting process is characterised by physico-chemical phenomena that are considered in the macro- and microscale. This paper attempts to assess the impact of local changes in the hydrodynamics of liquid steel flow in a one-strand slab tundish on the behaviour of the alloy addition, and consequently, the chemical homogenisation of the liquid steel entering the mould. Four variants of feeding the alloy addition to the liquid steel were considered. Water glass model was used for laboratory experiments. A tracer was fed into the water using the pulse-step method. Based on the mixing curves, the mixing time was calculated. Based on the laboratory experiments carried out, it has been found that, the alloy addition feeding site affects the mixing time, both for symmetric and asymmetric feeding relative to the longitudinal axis of the tundish.