The filter underdrain is one of the most important components contributing to overall filter performance. DNWT offers two categories of filter underdrains: dual parallel lateral underdrain products including DE NORA TETRATM U, LP, and Anchor-Rite® BlocksTM, and SNAP T® Block systems that provides a unique non-clogging underdrain for heavily-loaded applications. Both types of underdrains accommodate a wide variety of granular media types and sizes that are preferentially configured to provide the benefits associated with a DeepBedTM filtration concept. The underdrains provide excellent distribution of backwash air and water for efficient bed cleaning and low filter operating costs for new or retrofit applications. These underdrains are simple to install, require minimal maintenance, have no moving parts vulnerable to wear, and provide consistent performance over a long life.