How should waste from a commercial type dishwasher be piped?

The correct approach for piping waste from a commercial-type dishwasher is to do so indirectly to a 2" floor sink. This method is essential for food service establishments to prevent contamination or backflow into the plumbing system.

By using an indirect waste system, the dishwasher discharges its wastewater into a floor sink, which acts as an air gap between the wastewater and the plumbing drainage system. This air gap is crucial because it helps to prevent any potential cross-contamination by ensuring that no waste can flow back into the dishwasher or the potable water system. The size of the floor sink, in this case, being 2", is compliant with typical regulations for commercial kitchen drainage and is adequately sized to handle the volume of wastewater produced by the dishwasher.

While a direct connection could seem simpler, it poses significant risks and does not conform to sanitary plumbing practices. The design must ensure that wastewater is properly and safely managed, which is why indirect waste piping is the preferred and required approach in the context of commercial kitchens.