Double-wall rigid PVC drainage pipe

Basket filters are characterized by a double walled filter system - that is two concentric micro-slotted pipes coupled together through threaded flanges.
The cavity between the two is filled with filtering material such as siliceous gravel, calibrated according to the stratification of the ground.

These filters can be used to reclaim wells clogged with sand and as permanent drainage systems (easy to clean from lime scale) etc.