The invention relates to a drum filter for water filtration and method therefor. The drum filter comprises: a housing; a filter drum arranged in the housing and comprising a filter surface, wherein the filter drum is rotatable around a shaft; an inlet for supplying water for filtering to an outward facing side of the filter surface for the purpose of collecting fouling on the filter surface; an outlet for discharging filtered water; and a sprayer for spraying clean the filter surface, wherein the sprayer is configured to spray substantially transversely over the outward facing side of the filter surface.