Patent ID: 7141164

Claim:
An underdrain block for a filter system comrising an infrastructure, the underdrain block comprising: a housing defining a cavity; the housing comprising a top wall, a bottom wall, a first end wall, a second end wall, a first side wall and a second side wall, the end walls and side walls connecting the top wall to the bottom wall; the top wall defining an opening into the cavity; and one or more snap-locking mechanisms on the side walls, the snap-locking mechanism comprising wedge-shaped lugs, integral with and projecting from the side walls; the snap locking mechanisms further comprising a first set of wedge-shaped lugs positioned on the first side wall, the lugs projecting downward towards the bottom wall, each downward projecting, wedge-shaped lugs along with the first side wall defining a notch; and a second set of wedge-shaped lugs positioned on the second side wall, the second set of lugs projecting upward towards the top wall, each of the upward, wedge-shaped lugs along with the second side wall defining a recess so that adjacent underdrain blocks are interconnected by the projecting lugs when the first set of lugs is snapped into the second set of lugs; wherein each downward projecting lug comprises an end, the end machined to fit snuggly when snapped into the recess of the upward projecting lug and each upward projecting lug comprises a nib, the nib comprising a lip machined to fit within the notch of the downward projecting lug.