Current procedures for the design of filters to protect the soil from erosion and piping are solely based on particle-size distribution (PSD) curves of the filter medium and base soil. In the present work, an analytical solution is presented in a single derivation for the design of the filter, which takes into account factors like pore size, permeability, and factor of safety against soil boiling conditions. The solution obtained from the proposed analytical procedure provides insight into the role of seepage velocity, relative density of the filter material, and the ratio of filter density to base soil density on the performance of the filter.Key words: filter, erosion, particle-size distribution, permeability, seepage velocity, relative density.