A continuous strainer is a self-cleaning strainer that consists of a housing, a rotatably driven shaft mounted on the housing. A primary and a secondary drum concentrically mounted on the shaft and rotatable therewith, the drums having a number of perforations and strainer inserts mounted in each of the perforations. Each drum is provided with a reduced pressure backwash zone outside the drum and connected to backwash outlet connected to atmospheric pressure whereby, when a strainer insert passes the reduced pressure zone, pressurized liquid inside the drum forces liquid backwardly through the insert to flush accumulated solids there from. Backwashing operation can be commenced by means of a valve disposed in the backwash outlet lines and actuated by a timer or by a pressure differential switch, or both.