Abstract: A self-cleaning filter installed in a cylindrical conduit for a liquid to be cleaned, such as cooling water for an industrial power plant, comprises a sieve spanning the conduit and undulating between an upstream and a downstream transverse plane. The interior of the conduit is divided into two or more sectoral compartments which are bounded by corresponding sieve segments on the downstream side and are provided with respective peripheral outlets leading to a drain, these outlets being normally closed by associated shutoff valves. To clean any sieve segment bounding a particular compartment, the upstream entrance to that compartment is obstructed by a flap valve while the corresponding shutoff valve is opened to generate a reverse flow across that sieve segment.