PURAIN 6″ to 16″ Pre-Filters – External and In-Tank


If you are looking for a self cleaning filter with maximum capture efficiency, the PURAIN Jump Filter is for you. The key to the design of Intewa’s PURAIN filters is the hydraulic jump. Up to a certain rainfall rate, rainwater capture is 100%, something no other self cleaning filter can claim. The point at which hydraulic jump occurs accounts for around 97% of all rainfall in most regions, so actual total filter efficiency is over 98% over the course of a year.


When hydraulic jump occurs, the filter screen is naturally and vigorously cleaned. This happens 4-10 times a year in most regions.

The hydraulic jump simulates what happens in a stream when water flows over a drop caused by stones. More…



PURAIN industrial sized filters have 6″ to 16″ inlets which accommodates a wide range of roof square footages and maximum flows. All filters in this range can be mounted either inside the rainwater tank or externally. Please consult our sizing guide by clicking here.  The size you will need depends upon the rainfall intensity in your area and roof square footage.

Here are the key features of the PURAIN filters:

HD Purain Benefits

Here are some additional resources on the Intewa PURAIN pre-filter series:

Specification PURAIN DN150-S 

Specification PURAIN DN200 to DN400

Flow Evaluation of 6″ to 12″ PURAIN Filters

Comparison of 4″ PURAIN to other self cleaning filters

PURAIN Brochure

Drawing 8″pdficon

Drawing 12″pdficon

Drawing 16″pdficon

Technology Overview