Self-cleans with 98 % efficiency

Low rainfalls

Low rainfall events account for over 97 % of total annual rainfall. Therefore, it is particularly important that the filter be designed to collect this light rainfall. While many filters are not designed to collect light falls, the rainwater collected in the hydraulic jump filter tray is then filtered and drained into the tank. The tray ensures that no precious water is lost.

High Rainfalls

High rainfall events, that occur approx. 4 to 10 times in a year, contribute only about 3 % to total water yield and are used by the PURAIN Rainwater filter for self-cleaning. These high rainfalls lead to the formation of an eddy in the PURAIN rainwater filter, the so called hydraulic jump, which spins with such great force that even dirt accumulated in the tray is flushed and discharged with the overflow.

The PURAIN Rainwater filter cleans itself during heavy rainfall events. It means minimum maintenance costs for the user in comparison to other filter systems.  An overall rainwater filtering efficiency of 98 % is achieved with the unique, self-cleaning PURAIN Rainwater filter. 
With the hydraulic jump filter, this water is collected in a tray, which is then filtered and drained into the tank. The tray ensures that no precious water is lost. 3.5 kg of sand-gravel mixture was flushed away in just 30 seconds during this trial (see photo) due to the efficiency of the hydraulic jump.