The paper considers the problem of preserving the filtration properties of the drainage material in the zone of seasonal freezing. Studies have shown that drainage can lay in the zone of seasonal freezing, but the pores in the filter should not be completely filled with ice. The drainage filter may include a geotextile. The article introduces the filtration model, taking into account the freezing of water in the geotextile. The model analysis allows obtaining conclusions about changes in the porosity and the coefficient of filtration of geotextile with according to changes in ice content. The diameter of the geotextile fiber, the initial porosity and the experimentally determined water loss geotextiles are considered. The formulas relating these parameters are found. The results can be applied for the selection of geotextiles used in the zone of seasonal freezing for the drainage protection or as separating filter layers in the soil.