Liquid filtration device with backwashing feature

A liquid filtration device comprising a housing having a central axis, an outlet and an inlet, a plurality of cartridge filters each having opposite ends and a central bore extending from one end to the other end thereof, said filters being arranged in a circular orientation within said housing with each filter central bore generally paralleling and being generally equal angularly spaced apart from said housing axis, a first plate extending across each filter one end and a second plate extending across each filter other end, said second plate extending between said housing inlet and outlet and having a plurality of openings therein each aligned with a said filter central bore whereby liquid entering said housing inlet passes inwardly through each of said filters and into the aligned central bore thereof and then through the aligned second plate opening and out said housing outlet, a third plate located between said second plate and said housing outlet, said third plate having an opening and being shiftable between a first position spaced from said second plate in response to said liquid flow through said housing from said inlet to the outlet thereof and a second position next to said second plate in response to liquid flow through the housing from the outlet through said third plate opening and an aligned second plate opening and filter central bore outwardly through the filter of said last mentioned aligned central bore to said housing inlet, and an activator for rotating said third plate relative to said housing and second plate when the third plate is in its second position to sequentially align said third plate opening with each second plate opening.