Soil water repellency causes low infiltration rates and increased surface runoff resulting in less soil water storage as a supply to plant growth. Water repellency is thought to appear on dry soils, when the water content falls below a critical level. The main objective of this study was thus the determination of this critical water content for five soil types (pallic, recent, brown, organic and gley) from ten different sites under pastural land use on the north island of New Zealand. The second aim of the study was to find out when and how often during the year water repellency is likely to occur. This was done with the help of a water balance model and the previously determined critical water contents. Occurrence and gravity of soil water repellency was measured in the laboratory on both undisturbed and disturbed soil samples with the Water Droplet Penetration Time Test (WDPT) and the Molarity of Ethanol Droplet Test (MED). Measurements were started on nearly saturated samples and then repeated every day, while the samples were air- drying. When the samples reached a reasonably dry state, they were rewetted and another test cycle was started. All samples were found to be water repellent at least temporarily. Repellency tests confirm that water repellency does not exist on soils with water contents higher than 0.50m/ m. The critical water contents showed- depending on the different soil orders- values between 0.32m/ m and 0.50m/ m. In the modelling part, the water content in the top soil layer was simulated by the help of a water balance model every day for the time between April 2008 and April 2012. The modelled water contents fell below critical water contents during two to three thirds of a year of average annual precipitation. This happened more frequently in summer than in winter. Repellency- induced surface runoff was found to be a considerable issue in regions where high rainfall intensities are combined with high critical water contents.