Why Your Dishwasher Needs a High-Loop Drain (And How to Check If It’s Installed Correctly)

A seemingly small detail in your kitchen plumbing—your dishwasher’s high-loop drain—is critical in keeping your home safe from contamination and costly plumbing issues. In fact, the North Carolina Residential Code (NCRC) mandates its installation to maintain proper backflow prevention and sanitation standards. Let’s explore why this detail is essential, how it keeps your dishwasher running efficiently, and how to check if yours is installed correctly. What Is a High-Loop Drain? A high-loop drain involves routing the dishwasher’s drain hose to rise as high as possible under the kitchen sink—typically secured to the underside of the countertop—before descending to the drain or garbage disposal. This creates a “high loop” that prevents wastewater from your sink or garbage disposal from siphoning into the dishwasher. Without a high-loop installation, you risk cross-contamination from dirty water backing into your dishwasher, resulting in foul odors, harmful bacteria growth, and potential a...