This specification describes an intake filter for use, for example, in a system that collects greywater from baths or showers for re-use in toilet flushing. The intake filter provides essentially dead-end filtration. An influent by-pass may be provided, but the filter is cleaned as required to reduce use of the by-pass. Cleaning is performed when permeability of the filter declines. An upstream sensor may be used to detect the permeability of the filter. In one cleaning method, flowing water, optionally with air, is used to backwash the filter. The impulse of the flowing water also moves one or more valves to direct backwash water to a sanitary drain. For example, pumped effluent may impinge against a first flap to close an effluent drain, the first flap being mechanically linked to open a flap covering the sanitary drain.