Enviroquip® Folded Plate Filter Underdrain

The Enviroquip® folded plate filter underdrain is synonymous with proven performance in gravity filtration. A low profile, media retaining design allows for deeper media stacks than what is available with other underdrains. Our 0.25mm openings place filter media directly on the underdrains and air laterals. The uniform introduction of air and water through separate conduits provides superior simultaneous air/water cleaning. The system can be installed new or retrofit into existing filters.
  • Low headloss
  • Retains filter media (no support gravel)
  • Low profile allows deeper media bed
  • Separate air/water laterals eliminates surging action
  • Superior cleaning with less washwater

The Enviroquip® folded plate filter underdrain is installed using stainless steel anchors to fit most existing installations with ease. Low head through the filter increases filter efficiency. Media retaining design eliminates the need for a gravel layer, increasing the effective media depth allowable. Simultaneous air and water backwash efficiently and thoroughly cleans the media, eliminating mudballs.


  • Uniform cleaning improves filter bed performance
  • Enhanced air scour prolongs media bed life and reduces washwater volume
  • Lower air scour rate equals lower capital costs and lower energy use
  • Strong, permanent stainless steel design is maintenance free

The Enviroquip® folded plate filter underdrain provides vigorous agitation with the combination of air and water simultaneously during the backwash cycle. The addition of air not only enhances media cleaning, but significantly reduces the amount of backwash water required. Provided through a separate conduit, conventional air/water alternating backwash method is also available.

Enviroquip_ Folded Plate Filter Underdrain_IMG_1


Simultaneous Air + Water.


Enviroquip_ Folded Plate Filter Underdrain_IMG_3

Separate air and water laterals provide superior simultaneous air + water backwash. Uniform distribution of air and then water is virtually instantaneous during simultaneous air + water backwash. Other systems introduce the air and water through the same laterals and orifices creating surging action and non-uniform air + water distribution resulting in poor, uneven filter media cleaning. The Enviroquip folded plate underdrain + air scour simultaneous air + water backwash reduces the volume of water required to clean a filter by up to 50 percent, a potential benefit to all municipal utilities.

I’m thinking of doing a filter retrofit at my plant. Can you retrofit clay tile block underdrains?

Yes. We can retrofit clay tile blocks, wheeler bottoms, nozzle style underdrains, and header laterals.

I don’t have air backwash. Does air scour make that much of a difference?

Yes, it can make a huge difference. Our simple operation of air and water simultaneous backwash can save as much as 50% of the washwater required per backwash.

Can my plant staff do the retrofit? How long does it take? I can’t afford to stay down for long at my plant.

There are a few construction tolerances to consider, but the simple installation techniques require fewer installation man-hours than any other filter system. We will gladly discuss this money saving equipment with you if you’d like to consider it.

Do you offer backwash troughs and filter media?

Yes. We also offer local filter controls.

Can the lower profile media retaining design allow deeper media depths?

In most cases, yes it can. The 6 inch high underdrain in combination with the elimination of support gravel allows room for additional media depth without the risk of carryover.

nous contacter