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  • 3P Retention Filter with integrated Stainless Steel dirt retention basket for roof areas up to 800m2.
  • How the 3P Retention Filter XL works to clean Rainwater before it is stored in a Water Storage Tank.
  • Installation example of the Retention XL Filter fitted inside a water storage tank.
  • Installation example of the Retention Filter XL fitted in a soakway.
  • Dimensions of the Retention Filter XL.

Retention Filter for Roofs up to 800m2


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Product Description

Soakaway/Infiltration Crate SuDS Filter for Roof areas up to 800m2

Rainwater Retention Filter to 45l/sec max flow. For installation before storm tanks and flow control chambers. This 3P Technik filter is ideal to prevent and reduce blockages where water is  infiltrated to groundwater via a gravel soak-away or via plastic geo-cellular  crates, or via attenuation tanks or retention crates within an overall SUDs System.  This Retention Basket Filter can help to further protect infiltration products like Permavoid, Stormbrixx, Aquacell, Polystorm,StormCrate, Aquavoid etc.

The cleaned water can also be used in RWH stormwater and surface water re-use systems for supply to irrigation, garden watering, car washing etc. There is a risk of dis-colouration of the water being held in the storage tank because this is a retention filter, and therefore we do not recommend this Retention Filter is used for RWH in properties where water is used in buildings.

Low maintenance, depending on the level of solids (TSS) in the incoming rainwater. The stainless steel filter basket is easily accessed. The filter can then be removed for cleaning. Twice yearly inspections of the filter are recommended.

It comes complete with a push seal lid.

The Inlet and Outlet Connections can be cut to suit your pipework. The design of the unit allows for either DN150 or DN200 connections.

Silt Traps for Drainage and SUDs

The 3P retention filter can also be used as a silt trap for drainage and SUDs systems. The filter basket will retain microplastics in sediments down to 0.55mm (550 microns).

It is ideal as a plastic litter filter, preventing micro-plastics and larger plastics reaching waterways and the sea. 

How it works

(see also the diagram above)

  1. Rainwater flows into the filter basket.
  2. The dirt is retained in the dirt collecting basket. The basket has to be emptied and cleaned as necessary.
  3. One inlet DN 150/200 can also be used as an emergency overflow.
  4. Cleaned water flows through the bottom outlet DN 150/200 into the rainwater tank or soakaway.
  5. Use of a calmed inlet is possible in tanks to prevent sediment disturbance.

Technical Information

  • Max Roof Area: c800 to 1200m2, depending on project design rainfall intensities. 45l/sec max flow rate. 
  • Pipe Connections: DN150 or DN200
  • Housing Material: Polyethylene, colour: Blue
  • Filter: Stainless Steel
  • Filter Mesh: 0.55mm
  • Weight: 10Kg


Retention Filter XL Installation and Operating Instructions (pdf).

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