8 Arm Tree Double Percolator for water pipes. These water pipes percolator is meant for heavier glass pipes. Both joints on these percolator water pipes are 14mm. The first chamber of these water pipes percolator will collect your ashes and as the smoke travels to the second section of percolator it will go through a cleaning process and any additional matter will be filtered out. This will complete the process of percolator and it will move to the water pipes attached to it.