Brochure | November 2, 2011

Brochure: TETRA® SNAP T® Block Underdrain

Source: De Nora Technologies

The TETRA® SNAP T® Block underdrain from Severn Trent Services is a proven design of filter underdrain offering superior distribution of both backwash air and water, concurrently. The revolutionary design further enhances block stability during backwash procedures and features additional passive interlocking as well as positive row spacing for improved backwashing distribution.


  • Heavy total block weight of 24 kg (53 lb); grout or anchored hold-down system not required
  • Robust design constructed of 351 kg/cm2 (5000 psi) concrete and HDPE
  • Interlocking design does not need to be grouted down; no hold down anchors required
  • No moving or wearing parts
  • Corrosion resistant design
  • Easy maintenance and simple installation
  • Long life


  • Excellent distribution of backwash air/water – more efficient bed cleaning and reduced filter operating costs
  • Reduced installation costs and time
  • Interlocking grid throughout entire filter bottom resists uplift, even from a water hammer event
  • No maintenance requirements
  • Weight of block prevents lifting
  • Expected life of 35 to 50 years

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