Abstract: A method of depth filtration of particles from a fluid carrying particles including providing in a deep filter a quantity of filter medium elements, at least some of the elements being ionically conductive, applying an electric field to the deep filter to cooperate with individual the elements, permitting or causing said fluid with particles to flow into the deep filter, influencing the movement of particles in the deep filter by the electric field to enhance the filtration of the particles from the fluid. Suitable elements are polyacrylic fibers treated with caustic soda to modify the surface charge, where the electrical conductivity of the fibers vary within individual fibers and between different fibers. The application also concerns an apparatus where the filter medium is supported by a plastic mesh. Disc electrodes permit drinking water to be purified.