WWETCO FlexFilter™ CSO and Tertiary Treatment

WWETCO FlexFilter compressible media

WWETCO FlexFilter™ Combined Sewer Overflow (CSO) and Tertiary Treatment Overview:

The WWETCO FlexFilter™ is a high rate filtration system utilizing synthetic compressible media. The compression of the media is accomplished through a lateral hydraulic force applied from the incoming liquid. This unique method of compression eliminates mechanically actuated internal components and provides for a tapered compression of the media.

The varied porosity of the compressed media bed allows for increased filtering capacity as well as the ability to treat flow streams with higher solids concentrations while minimizing backwash cycles. In addition to the filter's ability to handle higher solids to the filter, the backwash system with air scour and specialized backwash troughs minimize the volume of backwash water needed. The combination of media compression method and backwash system makes the WWETCO FlexFilter™ one of the most versatile and efficient filters on the market.

How it works:

The WWETCO FlexFilter™ is a simple gravity system requiring no moving parts. The influent liquid applies a hydrostatic force to the compression bladder causing the media to compress. The tapered compressions provide for densely compressed media at the bottom that graduates to an expanded bed toward the surface.

As the liquid flows onto the top of the media, the larger particles are trapped in the upper portions of the filter. As the liquid works its way down, the smaller particles are captured. This porosity gradient within the filter bed allows for a more effective use of the entire media bed and allows for a higher mass load to the filter prior to backwash. As the filter bed becomes plugged, the influent level increases signaling the need for a backwash.

For the backwash, the feed to the filter is stopped, allowing the media to uncompress. The air scour is initiated along with a small amount of backwash water. The length of the backwash cycle is adjustable. Once cleaned, the filter is put back into service.

Pilot Program and Rental Equipment: We offer multiple pilot and rental options, whether for trial of the equipment for your specific application or renting a filter to meet a need.

WWETCO FlexFilter rendering


  • Can be applied for a number of uses or even combined uses
  • Passive design that does not require special attention or chemicals


  • No moving parts
  • Low backwash requirements
  • No ramp-up time
  • High loading rates
  • Minimal backwash


  • CSO and SSO treatment
  • Storm water runoff
  • Replace primary sedimentation
  • Tertiary treatment
  • Tertiary treatment for chemical phosphorus removal
  • Raw water pre-treatment         
  • Industrial water pre-treatment
  • Dual purpose tertiary treatment and CSO/SSO during storm event