A fluid filter device comprising: a primary filter section having a first porous section comprising a vertical cylindrical axial filter screen; said first porous section having an exterior surface an interior surface and a secondary filter section having second porous section comprising a vertical cylindrical axial filter screen; said second porous section having an exterior surface and an interior surface; wherein: (i) the primary filter section and the secondary filter section are in fluid communication with one another, and (ii) the first porous section has a greater porosity than the second porous section, the first porous section being the coarse porous section and the second porous section being the fine porous section, so that the fluid that is treated is subjected to: - an initial filtering action by said coarse porous section, the larger particles aggregating on said exterior surface of said coarse porous section and then to - a second filtering action by said fine porous section, the fine particles aggregating on said interior surface of said fine porous section, characterized in that said fluid filter device comprises further: a fluid backwash valve element located at the lower end of the coarse porous section to remove said aggregated larger particles, and operable between: (i) a closed position in which fluid flow is in a direction from the coarse porous section to the fine porous section during normal filtering operation, and (ii) an open position wherein at least a portion of the fluid flow is in a direction from the secondary fine porous section to the primary coarse porous section during backwashing; an annular cleaning ring disposed on the outside of said second porous section and capable of moving axially along said exterior surface of said second porous section to remove said aggregated fine particles therefrom with the help of pressurized fluid supplied to said annular cleaning ring. a primary filter section having a first porous section comprising a vertical cylindrical axial filter screen; said first porous section having an exterior surface an interior surface and a secondary filter section having second porous section comprising a vertical cylindrical axial filter screen; said second porous section having an exterior surface and an interior surface; wherein: (i) the primary filter section and the secondary filter section are in fluid communication with one another, and (ii) the first porous section has a greater porosity than the second porous section, the first porous section being the coarse porous section and the second porous section being the fine porous section, so that the fluid that is treated is subjected to: - an initial filtering action by said coarse porous section, the larger particles aggregating on said exterior surface of said coarse porous section and then to - a second filtering action by said fine porous section, the fine particles aggregating on said interior surface of said fine porous section, - an initial filtering action by said coarse porous section, the larger particles aggregating on said exterior surface of said coarse porous section and then to - a second filtering action by said fine porous section, the fine particles aggregating on said interior surface of said fine porous section, a fluid backwash valve element located at the lower end of the coarse porous section to remove said aggregated larger particles, and operable between: (i) a closed position in which fluid flow is in a direction from the coarse porous section to the fine porous section during normal filtering operation, and (ii) an open position wherein at least a portion of the fluid flow is in a direction from the secondary fine porous section to the primary coarse porous section during backwashing; an annular cleaning ring disposed on the outside of said second porous section and capable of moving axially along said exterior surface of said second porous section to remove said aggregated fine particles therefrom with the help of pressurized fluid supplied to said annular cleaning ring.