The present invention relates to a filtering panel (100) for a disk filter and a disk filter for water purification, comprising a metal filter cloth (16, 116) such as a stainless steel filter cloth, pre-tensioned in both warp and weft directions and fastened to a frame (10, 110) comprising a peripheral portion (11, 111), which is integral with an inner grillwork (12) and which divides the inner area of the peripheral portion (11, 111) into fields (15, 115). The frame (10, 110) comprises a plastic material reinforced with glass fibers or carbon fibres such as polypropylene loaded with fibreglass in an amount of at least 20 weight percent. Each field of the grillwork (12, 112) has an area not exceeding 10% of the inner area of the peripheral portion (11, 111). The pre-tensioning of the filter cloth (16, 116) in both directions is from at least 20% of the yield stress of the cloth (16, 116). Further the present invention relates to a disk filter comprising said filtering panels (100) and method of making said filtering panel (100).