Rainwater PreFilters


Intewa USA – Purain Rainwater Prefilters

Introducing Intewa, manufacturer of the Purain hydraulic jump filter. This hydraulic jump technology cleans itself automatically during a heavy storm. The design inspiration comes from nature: you see it in streams. As water flows over large rocks, a swirling eddy forms at the base. The stones are washed clean by the hydraulic force.

During lighter rainfall, the filter is 100% efficient. This is very different from other designs, where the first (only?) rain washes away.

The 4" and 6" sizes are molded plastic, and the larger sizes are fabricated from plastic sheets.

See the chart below for sizes and recommended flow rates:

SDR 35 Pipe Size Max. Flow Rate Rooftop Area (Atlanta) Above-Ground Model Inlet Centerline to Filter Top Below-Ground Model Invert*
4" 0 - 90 gpm 1500 s.f. PR100 3" 1.97"
6" 60 - 270 gpm 5000 s.f. PR150S 4.1" HD150 5.9"
8" 270 - 576 gpm 10,000 s.f. PR200 5.4" HD200 6.1"
12" 577 - 1684 gpm 30,000 s.f. PR300 8.75" HD300 10.7"
16" 1685 - 3630 gpm 70,000 s.f. PR400 10.2" HD400 13.62"

* The "Invert" in the chart above is the drop from inlet to outlet. These are some of the lowest in the industry, and allow for filters to be installed inside tanks, out of sight.

The below ground models are suitable for direct burial, and have an access opening for filter cleaning. ​