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Preferential flow of water and transport of solutes in a drained, dual-porosity soil, occurs due to macropores present in a ripened and structured clay field soil. Concentrations of the stable, natural isotope 18δ in drainage water indicate preferential flow. A numerical model is used to simulate two-dimensional variably saturated water flow and solute transport using a finite element solution of a set of two fully coupled equations describing the flow and transport in each individual flow domain, soil matrix and macropores. The specific characteristics and variation of 18δ in rainfall are represented in this paper by a non-adsorbing solute. Using steady-state flow conditions, the solute transport is modeled. Vertical flow and outflow drainage is dominated by macropore flow. Fast response to solute input concentrations of concentrations in macropore domain compared to the response in matrix domain concentrations shows preferential flow effects.