What is the required height of the discharge pipe for a dishwasher before it connects to the disposer?

The required height of the discharge pipe for a dishwasher before it connects to the disposer is at least 4 inches. This measurement is important for preventing backflow of wastewater from the disposer into the dishwasher, which can create sanitary issues. By ensuring the discharge pipe is elevated 4 inches above the drain inlet of the disposer, it helps maintain proper drainage and ensures that the water flows correctly out of the dishwasher while reducing the risk of contamination.

This height is a key aspect of plumbing code requirements that help ensure safe and efficient operation of appliances. While the other options suggest higher elevations, they exceed the minimum necessary to mitigate the risk of backflow, thus creating unnecessary complexity without added safety benefits. The focus is on practical application within the standards outlined in the International Residential Code.