A filter for a shore hole or gully trap

A dished shaped filter 18 for a shore hole, or gully trap, comprises a substantially square base 19 from which four substantially trapezoidal sidewalls 20 extend upwardly and outwardly to form a substantially square open mouth. Holes 22 are formed in both the base and the sidewalls. In use the filter is supported within a pipe adaptor 11 below a grille 14. The relative sizes of the holes in the filter 18 and the apertures in the grille 14 are such that the filter will trap particles of material small enough to pass through the grille but too large to pass through the filter. The presence of holes 22 in the sidewalls of the filter 18 allow air to escape in conditions of heavy rain. The filter 18 may also be formed as a segment of a sphere giving a bowl-shaped configuration.